JP2002135231A - Communication device, communication system, transmission control method for communication device, and medium providing control program - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a communication device or the like that can perform normal communication even in a poor communication environment. SOLUTION: A plurality of division means for dividing transmission data into different sizes, a header generation means for generating a header portion including information necessary for transfer of transmission data, a header generated by the header generation means, Transmitting means for transmitting, as a packet, transmission data divided by a predetermined dividing means of the plurality of dividing means; transmission determining means for judging whether the packet transmitted by the transmitting means has been normally transmitted; When it is determined by the determination means that the transmission has not been normally performed, the transmission data is re-divided by a second division means different from the predetermined division means, and the re-divided transmission data and the header generation means Retransmitting means for transmitting the regenerated header and the packet as a packet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication device such as a wireless communication device for performing wireless communication in packet units.

[0002]

2. Description of the Related Art Conventionally, wireless interfaces have advantages such as no complicated wiring, but have low interconnectivity.
Due to the low transfer rate and the high price of the device, it has not been widely used.

However, in recent years, standardization work has been actively conducted, and IEEE Std. Starting with the standards of 802.11-1999, IEEE Std. 802.11a-199
9, The standard of IEEE Std802.11b-1999 has been established. In particular, IEEE Std. 802.1
1b-1999 is a standard capable of transmitting data at a maximum of 11 Mbps using radio waves in the 2.4 GHz band, and thereby, a wired LAN (Local Area Network) is used.
rk) IEEE Std. A transfer rate equivalent to 10BASE-T (transfer rate: 10 Mbps) standardized in 802.3 can be supported.

[0004] Further, as the price of the wireless interface device has been reduced, the number of cases where the wireless interface device is adopted as a construction of a home network or as a small office LAN has been increasing.

FIG. 7 is a block diagram showing an example of a general construction of a wireless LAN.

Stations (1),..., (N) in the figure
Represents a plurality of stations, which are PC (P
An information device such as a personal computer (personal computer) is provided with an interface function for performing wireless communication. The access point 203 is a special wireless communication device, and is wirelessly connected to the stations (1),.
It provides a bridge function between N and a wired LAN. Also,
It is also possible to construct a wireless LAN only with stations (1),..., Station (n) shown in FIG.

[0007]

However, wireless L
In the AN, unlike the wired LAN, there is a high probability that external noise is mixed in the transmission path. In particular, IEEE Std. 80
2.4G used as carrier for 2.11b-1999
The range of the Hz band is not limited to the communication device for the wireless LAN, and is a band that can be used by various devices.
With the spread of 2.4 GHz band wireless devices, the amount of data packets transferred between communication devices is inevitably increased, which is expected to degrade communication quality.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide a communication device or the like that can normally communicate even in a poor communication environment.

[0009]

In order to achieve the above object, in a communication apparatus according to the present invention, a dividing means capable of dividing transmission data into different sizes, and information necessary for transferring the transmission data are provided. A header generating unit for generating a header portion including the header portion, and transmitting the header generated by the header generating unit and the transmission data of the first size divided by the dividing unit as a packet, the transmitted packet is normal. A transmission determining unit that determines whether the transmission data has been transmitted, and when the transmission determining unit determines that the transmission data cannot be transmitted normally, the division unit divides the transmission data into a second size. And control means for controlling the transmission data and the header generated again by the header generation means to be transmitted as a packet. That.

Further, in the communication apparatus according to the present invention, a dividing means for dividing transmission data into a first size or a second size, and a header generating means for generating a header section including information necessary for transferring the transmission data. Transmitting means for transmitting, as a packet, a header generated by the header generating means and the transmission data divided into the first size or the second size; and a transmitting state of the packet transmitted by the transmitting means. A communication device comprising monitoring means for monitoring, a first transmission control for transmitting the transmission data divided into the first size and the header generated by the header generation means by the transmission means, When the monitoring unit determines that the packet transmitted in the first transmission control has not been transmitted normally, the transmission data is reduced to the second size. And control means for performing a second transmission control for transmitting the divided data and the header regenerated by the header generating means by the transmitting means. I do.

Further, in the transmission control method for a communication apparatus according to the present invention, a dividing means capable of dividing transmission data into different sizes, and a header generation section for generating a header section including information necessary for transmitting the transmission data Means, and a communication device having a transmission means for transmitting the header generated by the header generation means and the transmission data divided by the division means as a packet. A transmission determining step of determining whether or not the data has been transmitted; and when the transmission determining step determines that the data cannot be transmitted normally, the division unit divides the transmission data into another size, and A retransmission process of transmitting data and a header generated again by the header generation unit as a packet is performed.

A medium for providing a control program for executing a transmission control method of a communication device includes a dividing unit capable of dividing transmission data into different sizes, and a header unit including information necessary for transferring the transmission data. A control program for executing a transmission control method for a communication device, comprising: a header generating unit for generating a packet; and a transmitting unit for transmitting, as a packet, the header generated by the header generating unit and the transmission data divided by the dividing unit. A medium to provide,
The control program includes: a transmission determination step of determining whether the packet transmitted by the transmission unit has been transmitted normally; and, when the transmission determination step determines that the transmission cannot be performed normally, the transmission data has a different size. And a retransmission step of transmitting, as a packet, the subdivided transmission data and the header generated again by the header generation means.

[0013]

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

FIG. 1 is a block diagram showing a configuration of a communication device according to an embodiment of the present invention.

The communication device of this embodiment is configured as one of the stations (1),..., (N) shown in FIG.

In FIG. 1, an MPU unit 303 is a control unit for controlling the entire apparatus. RAM (Random A
access Memory: random access memory)
The unit 304 provides a storage area for temporary work, and
An M (Read Only Memory) unit 305 provides a fixed storage area. Although not shown, an HDD (Hard Di)
If there is a device that provides a large-capacity rewritable storage area such as an sk Drive (hard disk drive), the configuration will be even more sophisticated.

An OS (Opera) for controlling the station
(Ting System: Operating system)
And application software are stored in the ROM unit 305 or an HDD (not shown), and the station operates by the MPU unit 303 executing control specified by the OS or application.

The I / O unit 306 provides an interface function with input devices (not shown) such as a keyboard and a mouse, and output devices such as a printer. A user's instruction is input to the station by the input device.

The display unit 307 provides an interface function with a display device such as a liquid crystal display or a monitor (not shown), and the display device displays a result specified by the OS or an application.

The antenna (PHY) unit 301 includes a transmission / reception changeover switch (not shown), an RF power amplifier, a low noise amplifier, an RF / IF converter, a dual synthesizer, a quad IF modem, and a baseband processor. ing.

The function of the antenna unit 301 is based on IEEE S
td. An antenna (physical) layer function conforming to 802.11b is provided.
A predetermined coding is performed on the transmission packet supplied from 02 and output to the air through an antenna. Conversely, it receives packets output from other stations,
The packet is decoded and supplied to the MAC unit 302 as a received packet.

The MAC unit 302 has the IEEE Std. 8
MAC (Medium Acc) compliant with 02.11b
ess Control: Provides the function of the medium access control layer. For this reason, the MAC unit 302 includes an interface unit with the MPU unit 303, an interface unit that controls the antenna unit 301,
The control unit includes a storage unit that stores operation steps of the MAC control unit, and a working memory unit.

In the station configured as described above, when data is transmitted by a user operation or the like, the I / O unit 306 notifies the MPU unit 303 of a data transmission request. In response to this request, the MPU unit 303
Sets information such as a transmission destination and a storage address of transmission data in the MAC unit 302.

In response to this setting, MAC section 302
The transmission data is read from the M unit 304 or the ROM unit 305, converted into a packet that can be received by the antenna unit 301, and supplied to the antenna unit 301. The antenna unit 301 adds a header and the like necessary for transmission to the received packet, encodes the packet, and outputs it to the air.

Conversely, when a packet addressed to itself is received, the packet received by the antenna unit 301 is decoded so as to be received by the MAC unit 302, and a packet from which an unnecessary header is removed is supplied to the MAC unit 302. You. M
The AC unit 302 extracts only the data portion from the received packet, and extracts the data portion from the RAM unit 3 designated by the MPU unit 303.
04 is written to the data. Data transmission and reception can be performed by wireless communication in such a procedure.

Next, the MAC section 302 and the antenna section 301
The format of a packet exchanged between the server and the server will be described.

This packet format is MPDU
(MAC Protocol Data Unit: M
AC protocol data unit)
(A) shows a format example of a general MPDU 401.

As shown in FIG. 2A, the MPDU 401
Is a MAC header field 402, a frame body field 403, and a CRC (Cyclic Redundant).
ancy check (cyclic redundancy check) field 404. The frame body field 403 is a data feed that is actually transmitted, and is defined as a variable length field from 0 to a maximum of 2312 bytes.

The CRC field 404 is a cyclic redundancy check calculated by a 32-bit polynomial for the MAC header field 402 and the frame body field 403. The CRC field 404 is calculated based on the received data and the value of the CRC field 404 after the reception. CRC field 404
Error detection is performed by comparing with the value of.

The MAC header field 402 includes a frame control field 405, a duration ID field, and an address (1).
~ (4) field and sequence control (Sequence Control) field 40
6 fields.

FIG. 2B shows the structure of the field of the frame control field 405.

As shown in FIG. 2B, the fields of the frame control field 405 are a protocol version field, a type field, a subtype field, a ToDS field, a FromDS field, a More Fragment (More Fragment) field 407, and a retry field. 408, PwrM
gt (Power Management) field, more data (More Data) field,
Each field is composed of a WEP field and an order field.

FIG. 2C shows the fields of the sequence control 406.
The control 406 includes a 4-bit fragment number field 409 and a 12-bit sequence number field 410.

FIG. 3 is a schematic diagram showing the division of a packet according to the present embodiment.
(MAC Data Service Unit: MA
C data service unit) 601 is shown when it is divided and transferred. The maximum size of the transmittable frame body field 403 is 2312 bytes. Therefore, if the MSDU 601 is divided and transmitted with this size, data is transmitted with the maximum packet length. It is not always necessary to transmit at the maximum length, and the value of the frame body field 403 to be transmitted is determined according to the capability of the station.

In the example of FIG. 3, the MSDU 601 is divided into four parts, and the data of each divided MSDU 601 is added to the MAC header field 402 and the CRC field 4.
04, the packet is packetized as four MPDUs, and each fragment (Fragment)
(0), fragment (1), fragment (2), and fragment (3) are numbered and transmitted.

At this time, the more flag field 407 of the frame control field 405 in the fragment (0) is set to 1, the fragment number field 409 of the sequence control field 406 is set to 0, and the sequence number field is set to 0. Set to n + 1. N at this time
Is the number of MPDUs transmitted until the previous transmission.

Subsequently, the frame of the fragment (1)
The More / Flag field 407 of the control field 405 is set to 1, the fragment number field 409 of the sequence control field 406 is set to 1, and the sequence number field is set to n + 2.

Similarly, in the fragment (2), the more flag field 407 is set to 1, the fragment number field 409 is incremented to 2, and the sequence number field is set to n + 3.

Finally, the frame of fragment (3)
The more flag field 407 of the control field 405 is set to 0, the fragment number field 409 of the sequence control field 406 is set to 3, and the sequence number field is n +.
Set to 4.

FIG. 4 shows a procedure for transmitting a packet for transmitting the data thus divided from the transmitting station to the receiving station.

In FIG. 4, initially, in a busy medium 501, a certain station is transmitting a packet. The transmitting station that wants to transmit the packet senses the radio wave intensity in the air, and after the transmission state of the packet ends, the DIFS (D
istributed coordinationfu
nction Inter Frame Space:
During the dispersion adjustment function frame interval (502), it is confirmed that no radio wave is transmitted, and CW (Conten
After a random time called a “window” 503, if another station does not transmit a radio wave, a packet can be transmitted.

When a packet becomes available for transmission, the transmitting station transmits a packet called an RTS packet 504. The RTS packet 504 has a format in which a CRC field 404 is added to the MAC header field 402. Being an RTS packet 504 means that
It is indicated by the value of the type and subtype fields of the frame control field 405. The address (1) stores the address of the transmitting station, the address (2) stores the address of the receiving station, and the other address fields and sequences. -The control field 406 is omitted.

When the receiving station receives the RTS packet 504, it receives a SIFS (S
After a short inter frame space (short frame time) 505, a packet called a CTS packet 506 is transmitted. The CTS packet 506 is also
This is a format in which a CRC field 404 is added to the MAC header field 402 as in the case of the RTS packet 504, and the frame control field 405
The type and subtype field values indicate that the packet is a CTS packet 506. R for address (1)
The value of the address (2) of the TS packet 504 is copied and stored. Other address fields and the sequence control field 406 are omitted.

The transmitting station that has received the RTS packet 504 determines that the subsequent packet can be transmitted, and transmits a fragment (0) 507, which is the fragment (0) described with reference to FIG. 3, after the SIFS 505.
Upon receiving the fragment (0) normally, the receiving station transmits an ACK packet 508 to the transmitting station after the SIFS 505, and sends the fragment (0) 50
7 is received. The format of the ACK packet is the same as that of the CTS packet 506.
The value of the type and subtype fields of the control field 405 indicates that the packet is the ACK packet 508.

If the transmitting station has more fragments to transmit, the SI following the ACK packet 508
After FS505, the fragment (1) described in FIG.
Is transmitted as fragment (1) 507. This sequence is continued until there are no more fragments, and transmission of all fragments is completed.

The CTS packet 506 after the transmission of the RTS packet 504 is not transmitted, or the CTS packet 5
For example, when the CRC field 404 of 06 is not a normal value, it is determined that the transmission sequence of this packet has failed. In this case, it is necessary to redo the packet transmission sequence from the beginning.

Similarly, if a similar situation occurs during the transmission of the fragment 507 and the transmission of the ACK packet 508, it is determined that the packet transmission sequence has failed. In this case, retransmission processing is performed from the fragment for which transmission has been determined to have failed.

Next, the characteristic processing of the present embodiment will be described with reference to FIGS. 5 and 6 are flowcharts showing a transmission sequence of the transmitting station according to the present embodiment. The control method described below can be realized by storing a program according to the flowcharts of FIGS. 5 and 6 in a storage device such as the ROM 305 in the station and operating the program.

When a data transfer request is generated by an application or a user's instruction, step S1 is executed.
At 01, a transmission request is notified from the MPU unit 303 to the MAC unit 302. At this time, at the same time, information such as the destination address and the storage address of the transmission data is also stored in the MAC
Passed to 2.

In response, at step S102, MA
The C unit 302 acquires transmission data stored in the RAM unit 304 or the ROM unit 305. This transmission data is the MSDU 601 in FIG. MSDU 601 is split into fragments of default frame body length,
Generate an AC header. In this example, the default frame body length is 1024 bytes.

In step S103, the MAC unit 302
The value of the fragment number field 409 of the fragment (0) to be transmitted first is set to 0. Also,
If there is a subsequent fragment, the more flag field 407 of the MAC header field 402 is set to one. If there is no following fragment, MA
More / Flag field 4 of C header field 402
07 is set to 0.

In step S104, fragment (0)
Of the sequence number field 410 is set. This value indicates the number of packets that have been sent to the station specified as the destination so far. MAC unit 30
A storage area is prepared in the working memory unit 2 and the initial value is set to 0, and this value is written in the sequence number field 410 of the fragment (0), so that the value incremented by 1 is stored in the working unit of the MAC unit 302. It is stored as an updated value of the memory unit for use. The next time this area is accessed, its value automatically becomes the sequence number field 410.

In step S105, the value of the retransmission counter is set to 0, and in step S106, the value of the retransmission flag is set to 0. The retransmission counter value and retransmission flag value are M
It is assumed that it is stored in the working memory unit of the AC unit 302.

In step S107, the transmitting station attempts to transmit the RTS packet 504. If another packet is being transmitted in the air, wait until the transmission of the packet ends, and the transmitting station sets the RTS.
It waits until the packet 504 can be transmitted.

As soon as the RTS packet 504 can be transmitted, the packet is transmitted, and the reception timer is started in step S108. After transmitting the RTS packet 504,
In steps S109 and S110, the reception wait state for the CTS packet 506 is entered. If the CTS packet 506 is received within the period of SIFS 505, step S1
The process proceeds to step S17, and if not received, a timeout occurs and the process proceeds to step S111.

In step S109, the CTS packet 506
Is received, in step S117, the CTS packet 50
6 is the expected value, and CR
Confirm that the value of the C field 404 is normal.
When it is confirmed that the CTS packet 506 has been received normally, the current value of the retransmission flag is determined in step S118. The description will be continued by assuming that the value of the current retransmission flag is 0.

When the retransmission flag is 0, step S119
Then, the transmission of the fragment (0) is performed with the size of the default frame body field 403. When fragment (0) is transmitted, a reception timer is started in step S122, and A is transmitted in steps S123 and S124.
The CK packet 508 waits for reception. SIFS5
If the CTS packet 506 is received within the period of 05, the process proceeds to step S117. If the CTS packet 506 is not received, the reception times out and the process proceeds to step S111.

The description will be continued assuming that ACK packet 508 has been received. ACK packet 508 in step S123
Is received, an ACK packet 50 is received in step S125.
8 is the expected value, and CR
Confirm that the value of the C field 404 is normal.
If it is confirmed that the ACK packet 508 has been received normally, it is determined in step S126 whether or not the MSDU 601 to be transmitted still remains. If there is no remaining MSDU 601 to be transmitted, the process proceeds to step S129, where it is notified that the transmission operation has been completed normally, and the transmission sequence ends. If the MSDU 601 to be transmitted remains, the process proceeds to step S127, and the value of the fragment number field 409 is incremented by one in step S127 to transmit the next fragment to be transmitted. The value is 1 for fragment (1) and 2 for fragment (2).

In step S128, the value updated in step S104 is set to the value of the sequence number field 410, and a value obtained by adding 1 to this value is stored as an updated value. When the generation of the MAC header field 402 of the fragment to be transmitted ends, the process proceeds to step S118, and the transmission sequence is continued.

When the transmitting station receives the RTS packet 50
4, the receiving station could not receive normally due to noise or the like, or the receiving station received the RTS packet 504 and transmitted the CTS packet 506 as equivalent, but the transmitting station could not receive normally. If not, a reception timeout occurs in step S110. At this time, the transmitting station proceeds to step S111, and adds 1 to the value of the retransmission counter.

In step S112, when the value of the retransmission counter is smaller than a value obtained by adding 1 to the maximum number of retransmissions defined as Max2, the process proceeds to step S113, and when equal, the process proceeds to step S116. In this example, the maximum number of retransmissions is 5.

In step S116, the maximum number of retransmissions of 5
The retransmission is attempted but not all MSDUs 601 have been transmitted, and the transmission sequence ends. After this, whether to transmit data again depends on an instruction of an application or a user.

When the process proceeds to step S113, if the value of the retransmission counter is smaller than the value obtained by adding 1 to the number of retransmissions defined as Max1, the process proceeds to step S114.
When they become equal, the process proceeds to step S115. In this example, the number of retransmissions is three.

When the process proceeds to step S114, 1 is set to the retransmission flag. In the case of step S115, 2 is set to the retransmission flag. Step S114,
In step S115, the process returns to step S107 to repeat the transmission of the RTS packet 504 again to transmit a fragment that could not be transmitted in the previous transmission sequence.

If ACK packet 508 could not be received in step S124, or if step S1
The ACK packet 508 received in step S23 is
If it is determined in step 5 that the transmission is not normal, the process proceeds to step S111, and the retransmission counter is similarly incremented and the retransmission flag is set.

When the retransmission counter is 1 or more, or when the retransmission flag is 1 or more, the retry field 408 of the MAC header field 402 is set to 1 to indicate that the fragment to be transmitted is being transmitted by the retransmission procedure. Set. When it is not a retransmission, the retry field 408 is set to 0.

If the fragment has been transmitted normally along the transmission sequence, the process proceeds from step S118 to step S119, and the fragment is transmitted with the default frame body size.

If retransmission is to be performed due to an error such as noise, but does not exceed the number of retransmissions, the process proceeds from step S118 to step S120 to transmit fragments with a frame body size shorter than the default. In this example, the short frame body length is 51
It is 2 bytes. When the size of the frame body field 403 is reduced in this manner, it is expected that the possibility of receiving external noise is reduced.

If the number of retransmissions is exceeded and the maximum number of retransmissions is not exceeded, in step S121, transmission is performed at a reduced transmission speed. In this case, the fragment is transmitted with a size smaller than the short frame body size described above. In this example, the short frame body length is 256 bytes. By doing so, it is possible to increase the robustness of the transmission sequence and further increase the probability of performing transmission.

The transmission sequence of this embodiment has been described in detail above. The transmission sequence will be further described with reference to FIG.

First, the MPDU 601 to be transmitted is divided into fragments in units of 1024 bytes, which is the default frame body size. Fragments are numbered from the beginning. In this case, it is assumed that the fragment is divided into four fragments (0), fragment (1), fragment (2), and fragment (3).

When the transmission sequence is performed normally, these fragments (0), (1), (2), and (3) are transmitted in order.

For example, when the ACK packet 508 cannot be received while transmitting the fragment (1), the frame body of the fragment (1), the fragment (2), and the fragment (3) is divided into 512-byte units. Then, the fragment numbers are reassigned to reconstruct fragments (0) ', (1)', and fragments (2) 'to (n)', and retransmission is attempted. This sequence is repeated up to three times, which is the number of retransmissions.

If a transmission error occurs even during transmission with this frame body size, the frame body of each fragment is further divided into 256-byte units, and a retransmission is attempted with the transmission speed reduced. This sequence is repeated twice with a value obtained by subtracting the number of retransmissions from the maximum number of retransmissions.

If transmission is still not successful, the result is notified to the application or the user, and the transmission sequence ends.

Here, the number of retransmissions and the maximum number of retransmissions described in the example are not particularly limited, and can be set to arbitrary values. Similarly, the size of the frame body is not limited.

In this example, the packet size is reduced from the first retransmission sequence.
In some cases, various combinations can be applied, such as adding a transmission sequence with the default size or changing the transmission speed first.

The present invention is not limited to the apparatus of the above-described embodiment, but may be applied to a system including a plurality of devices or an apparatus including a single device. A storage medium storing program codes of software for realizing the functions of the above-described embodiments is supplied to a system or an apparatus, and a computer (or CPU or MPU) of the system or apparatus reads out and executes the program code stored in the storage medium. It goes without saying that it will be completed by doing so.

In this case, the program code itself read from the storage medium realizes the function of the above-described embodiment, and the storage medium storing the program code constitutes the present invention. As a storage medium for supplying the program code, for example, a floppy (registered trademark) disk, a hard disk, an optical disk,
Magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, nonvolatile memory cards, and ROMs can be used. When the computer executes the readout program code, not only the functions of the above-described embodiments are realized, but also the OS or the like running on the computer performs the actual processing based on the instruction of the program code. It goes without saying that a case where some or all of the operations are performed and the functions of the above-described embodiments are realized by the processing is also included.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the program code is read based on the next program code. Needless to say, the extended function may be performed by a CPU or the like provided in an expansion board or an expansion unit to perform a part or all of the actual processing, and the processing may realize the functions of the above-described embodiments. No.

[0081]

As described above in detail, according to the present invention, even if the communication environment is deteriorated due to external noise or packet collision with another communication device, the communication sequence can be reduced. Can increase the probability of successful completion,
It is possible to always ensure high communication quality.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a communication device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a format example of a packet according to the embodiment;

FIG. 3 is a schematic diagram illustrating packet division according to the embodiment;

FIG. 4 is a schematic diagram of a transmission sequence according to the embodiment.

FIG. 5 is a flowchart illustrating a transmission sequence of a transmitting station according to the embodiment.

FIG. 6 is a flowchart continued from FIG. 5;

FIG. 7 is a block diagram illustrating a general configuration example of a wireless LAN.

[Explanation of symbols]

 201, 202 Station 203 Access Point 301 Antenna Unit 302 MAC Unit 303 MPU 304 RAM Unit 305 ROM Unit 306 I / O Unit 307 Display Unit 401 MPDU 402 MAC Header Field 403 Frame Body Field 404 CRC 405 Frame Control Field 406 Sequence Control Field 407 More Fragment field 408 Retry field 409 Fragment number field 410 Sequence number field 502 DIFS 503 CW 504 RTS packet 505 SIFS 506 CTS packet 507 Fragment 508 ACK packet 601 MSDU

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) H04L 29/14 H04L 13/00 313

Claims (22)

[Claims] 1. A dividing unit that can divide transmission data into different sizes, a header generation unit that generates a header section including information necessary for transmitting the transmission data, and a header generated by the header generation unit. A transmission determining unit that determines whether the transmitted packet has been normally transmitted when transmitting the transmission data of the first size divided by the dividing unit as a packet; When it is determined that the transmission data cannot be divided, the transmission data is subdivided into the second size by the division unit, and the subdivided transmission data and the header generated again by the header generation unit are transmitted as a packet. And a control means for performing the control as described above. 2. The communication device according to claim 1, wherein the second size is smaller than the first size. 3. The determination means also determines whether the retransmitted packet has been transmitted normally. If it is determined that the retransmitted packet has not been transmitted normally, the size of the transmission data is sequentially reduced. The communication apparatus according to claim 1 or 2, wherein the same operation as the retransmission processing is repeatedly performed up to a preset first number of retransmissions. 4. When the number of retransmissions is between the first number of retransmissions and a second number of retransmissions smaller than the first number of retransmissions, when the number of retransmissions does not reach the second number of retransmissions 4. The communication device according to claim 3, wherein the transmission speed is set to be lower than the transmission speed. 5. The communication device according to claim 1, wherein the transmission method of the transmission data is a wireless communication method. 6. A dividing unit that divides transmission data into a first size or a second size, a header generation unit that generates a header section including information necessary for transfer of transmission data, and a header generation unit that generates the header portion. Transmission means for transmitting, as a packet, the transmitted header and the transmission data divided into the first size or the second size, and monitoring means for monitoring a transmission state of the packet transmitted by the transmission means. A communication device, wherein the first transmission control for transmitting the transmission data divided into the first size and the header generated by the header generation unit by the transmission unit; and the first transmission control by the monitoring unit. When it is determined that the packet transmitted by the transmission control cannot be transmitted normally, the transmission data is subdivided into the second size, Communication apparatus characterized by comprising a control means for the second transmission control for transmitting the generated again by the transmission data the header generation unit header by the transmitting means. 7. The communication device according to claim 6, wherein the second size is smaller than the first size. 8. The division unit may divide transmission data into a third size, and the control unit may determine whether a packet transmitted by the second transmission control cannot be transmitted normally. ,
Performing a third transmission control for re-dividing the transmission data into the third size and transmitting the divided transmission data and a header generated again by the header generation unit by the transmission unit. Claim 6 or Claim 7
The communication device as described. 9. The communication device according to claim 8, wherein the third size is smaller than the second size. 10. The transmission control according to claim 8, wherein the third transmission control is set so that a transmission speed is lower than that of the first transmission control or the second transmission control. Communication device. 11. The transmission method of the transmission data is a wireless communication method.
The communication device as described. 12. A communication device comprising: a first communication device which is the communication device according to claim 1; and a second communication device which communicates with the first communication device. system. 13. A division unit capable of dividing transmission data into different sizes, a header generation unit for generating a header section including information necessary for transmitting the transmission data, and a header generated by the header generation unit. And a transmission unit that transmits the transmission data divided by the division unit as a packet, and a transmission determination step of determining whether the packet transmitted by the transmission unit has been normally transmitted; When it is determined by the transmission determination process that the transmission has not been normally performed, the transmission data is re-divided into another size by the division unit, and the re-divided transmission data and the header generated again by the header generation unit. And a retransmission step of transmitting the packet as a packet. 14. The transmission control method for a communication device according to claim 13, wherein in the retransmission process, transmission data is divided into a smaller size than a data size of a packet that cannot be transmitted normally. 15. A retransmission determination step for determining whether a packet transmitted in the retransmission step has been successfully transmitted is performed. When the retransmission determination step determines that the packet cannot be transmitted normally, the size of the transmission data is reduced. 15. A retransmission repetition step of dividing transmission data so as to become smaller sequentially and repeatedly executing the same processing as the retransmission step up to a preset first number of retransmissions. The transmission control method of the communication device according to the above. 16. When the number of retransmissions in the retransmission repetition process is between the first number of retransmissions and a second number of retransmissions smaller than the first number of retransmissions, the second number of retransmissions 16. The transmission control method for a communication device according to claim 15, wherein the transmission speed is set to be lower than at the time of retransmission that does not reach. 17. The transmission data transmission method is a wireless communication method.
7. The transmission control method for a communication device according to item 6. 18. A dividing unit that can divide transmission data into different sizes, a header generation unit that generates a header portion including information necessary for transmitting the transmission data, and a header generated by the header generation unit. And a transmission unit for transmitting, as a packet, the transmission data divided by the division unit. A medium for providing a control program for executing a transmission control method of a communication device, wherein the control program is transmitted by the transmission unit. A transmission determining step of determining whether the transmitted packet has been transmitted normally, and when it is determined by the transmission determining step that transmission has failed, the transmission data is re-divided into different sizes, and the re-divided A retransmission step of transmitting transmission data and a header regenerated by the header generation means as a packet. A medium for providing a control program characterized by the following. 19. The medium for providing a control program according to claim 18, wherein, in the retransmission step, transmission data is divided into a smaller size than a packet that cannot be transmitted normally. 20. The control program, further comprising: a retransmission determination step for determining whether the packet transmitted in the retransmission step has been successfully transmitted; and when the retransmission determination step determines that the transmission failed, the transmission A retransmission repetition step of dividing transmission data so that the data size is sequentially reduced, and repeatedly performing the same retransmission processing as the retransmission step up to a first retransmission number set in advance. A medium for providing the control program according to claim 18 or 19. 21. The retransmission repeating step, wherein when the number of retransmissions is between the first number of retransmissions and a second number of retransmissions smaller than the first number of retransmissions, the second number of retransmissions is reached. 21. The medium for providing a control program according to claim 20, wherein the transmission speed is set to be lower than at the time of no retransmission. 22. The transmission method according to claim 18, wherein the transmission method of the transmission data is a wireless communication method.
A medium for providing the control program according to 1.