JP2000151639A - Packet communication method in radio communication and packet communication device in radio communication - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain excellent communication compatible with a communication environment by optimizing a communication rate and error correction coding strength depending on the communication environment state of a location where a receiver terminal is located. SOLUTION: When a local terminal is a receiver side, it receives a transmission request packet (RTS packet) sent from a transmitter-side terminal, a communication environment state measurement means 25 measures the communication environment state of the local terminal at that instant and adds the measured result (communication environment measured data) to a reply packet (CTS packet) and returns the resulting packet to the transmitter-side terminal. When the terminal is a transmitter, after the terminal sends a transmission request packet (RTS packet), a communication parameter setting means 33 sets an optimum communication rate and an error correction coding strength matching the communication environment of a receiver terminal at that instant on the basis of communication environment measurement data in a reply packet (CTS packet) returned from a receiver-side terminal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a packet communication method and a packet communication device in wireless communication for performing mutual communication by packetizing data to be transmitted using an AN (Local Area Network).

[0002]

2. Description of the Related Art Wired LANs have been widely used as communication means between information processing apparatuses. The wired LAN is now capable of high-speed communication such as several Gbps (bits per second), and its speed and function are being further enhanced.

However, on the other hand, some problems of the wired LAN are being pointed out. For example, there are great restrictions on the complexity of cable installation and maintenance, as well as the location and relocation of information processing equipment connected to the LAN. In addition, there are various problems due to the wired connection. There is.

[0004] In recent years, the types of information processing devices have also become diverse. For example, even with a personal computer (hereinafter, referred to as a personal computer) as an example, portable devices such as notebook computers as well as desktop computers are rapidly spreading. If this kind of portable information processing device is used while keeping the feature of being portable, it is practically impossible to connect to a wired LAN.

[0005] In order to cope with this, attention has been paid to a wireless LAN which is a wireless LAN. Wireless LAN can eliminate various problems associated with cable laying, and can make the most of the portability of information processing equipment to be used.
Since it is possible to perform communication that could not be performed with a wired LAN, it is expected that technical development related to this wireless LAN will further advance in the future.

Under these circumstances, the working group 11 (IEEE 802.11) of the IEEE 802 standardization committee has focused on the protocol of the wireless LAN, focusing on the physical layer and the medium access control (MAC) sublayer specifications. ) Are being standardized.

[0007]

However, wireless L
There are also some problems in implementing AN. That is, in wireless communication, a signal transmitted from an antenna propagates in various directions in space and is received at a receiving side. In a situation where signal propagation is performed in such a multipath environment, In addition, fading that degrades signal quality, such as fluctuation and drop of electrolytic strength caused by a multipath environment, becomes a problem. In particular, indoors such as factories and the like have many obstacles such as walls, fittings, and people, and signal propagation paths are very complicated, so that fading countermeasures are required.

[0008] The communication speed of the wireless LAN (hereinafter, referred to as a communication rate) is the same as that of the above-mentioned IEEE8.
According to 02.11, it is currently usually 2 Mbps or 1 Mbps. This is an extremely low value compared to the communication rate of the wired LAN.

However, in view of future technical trends, a communication rate of 2 Mbps or 1 Mbps is too low, and there are many practical problems. Therefore, it is desired to realize a higher communication rate even in a wireless LAN.

[0010] This communication rate largely depends on the communication environment of the place where the information processing equipment (hereinafter referred to as a terminal) to be communicated exists. In other words, the higher the communication rate, the more easily the environment is affected by the environment. If an attempt is made to perform communication at a high communication rate in a bad environment, the rate of occurrence of errors increases.

For example, if the communication rate is up to 12 Mbp
s, at least 1 Mbps, and if there is a system in which the communication rate is divided into several stages and one of the communication rates can be selected, first, communication is performed at a high communication rate, and as a result, an error occurs. If the rate of occurrence is high, communicate at a lower communication rate,
It is necessary to optimize the communication rate by changing the communication rate stepwise according to the communication environment at that time to determine the optimum communication rate. In this case, efficient communication can be performed by performing communication at a high communication rate in a good communication environment and performing communication at a low communication rate in accordance with the environment in a bad communication environment. .

As a method of realizing this, for example, it is conceivable to make a test packet reciprocate between a transmitting terminal and a receiving terminal and select an optimum communication rate from statistical judgment.

By the way, in a stationary terminal such as a desktop personal computer, the communication environment does not change significantly unless the installation location is changed. Therefore, when performing communication by wireless LAN, the environment changes little. There is no need to consider this, and communication can be performed at an optimal communication rate known in advance without performing optimization processing each time.

On the other hand, when communication is performed by wireless LAN using a portable terminal such as a notebook personal computer, the environment may change depending on the location of the terminal. To select a communication rate according to the communication environment at that time. In particular, when data communication is performed from a mobile body such as an automobile, the communication environment changes every moment, and therefore, it is necessary to optimize each time.

Accordingly, the present invention sets an optimum communication rate and error correction coding strength in accordance with the communication environment condition of a place where a terminal to be communicated exists, and sets the set communication rate and error correction coding strength. An object of the present invention is to transmit data to be transmitted according to the strength, thereby enabling optimal communication suitable for a communication environment at that time.

[0016]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention relates to a packet communication method in wireless communication in which data to be transmitted is packetized using a wireless medium such as radio waves or light to perform mutual communication. Therefore, before the transmitting terminal transmits the data packet to be transmitted to the receiving terminal, a transmission request packet is transmitted to the receiving terminal mainly in order to secure a wireless transmission path. If the terminal can receive the transmitted transmission request packet,
In a packet communication method in wireless communication in which a communication procedure for returning a response packet indicating that reception is possible is performed, the receiving terminal measures a communication environment condition at a location where the receiving terminal is located, The obtained data is used as communication environment compatible data, and the communication environment compatible data is added to the response packet and returned to the transmitting terminal. On the other hand, the transmitting terminal, based on the communication environment corresponding data in the response packet returned from the receiving terminal, based on an optimal environment-adaptive communication parameter adapted to the communication environment of the receiving terminal at that time. The data packet to be transmitted is transmitted to the receiving terminal.

The present invention also relates to a packet communication method in wireless communication in which data to be transmitted is packetized using a wireless medium such as radio waves or light to perform mutual communication, wherein a transmitting terminal transmits a packet to a receiving terminal. A packet communication method in wireless communication for receiving a response packet indicating a reception state of the packet data from a receiving terminal after transmitting one or more data packets, and performing a next transmission procedure;
In the receiving terminal, every time the one packet data is sent, the communication environment status at that time is measured, and the data obtained thereby is used as communication environment compatible data. A response packet is added to the response packet and returned to the transmitting terminal, and the transmitting terminal determines the time of the receiving terminal based on the communication environment corresponding data in the response packet returned from the receiving terminal. The next data packet is transmitted to the receiving terminal by the optimal environment-adaptive communication parameter adapted to the communication environment in the above.

The present invention also relates to a packet communication apparatus for wireless communication in which data to be transmitted is packetized using a wireless medium such as radio waves or light to perform mutual communication, wherein a transmitting terminal transmits a response from a receiving terminal. In a packet communication device for wireless communication for receiving a packet and transmitting a data packet, a transmission / reception data generation unit having a communication environment condition measuring means for measuring a communication environment condition of a place where the own terminal is present, and the communication environment condition measurement Means for adding the communication environment compatible data obtained from the means to the response packet and outputting the data, and the communication environment compatible data in the response packet sent from another terminal to the own terminal. , A process for setting an optimal environment-adaptive communication parameter suitable for the communication environment of the other terminal at that time is possible. It is that it includes a communication control unit configured.

In the packet communication device in the wireless LAN having such a configuration, when its own terminal is a receiving side, the communication environment state of the place where the own terminal exists is measured, and the data obtained thereby is transmitted. The communication environment-compatible data is added to the response packet, and the data is returned to the transmitting terminal. Further, when the terminal itself is the transmission side, after transmitting the transmission request packet, based on the communication environment corresponding data in the response packet returned from the reception side terminal, the reception side The data packet to be transmitted is transmitted to the receiving terminal by an optimum environment-adaptive communication parameter adapted to a communication environment at a point in time.

In each of the inventions described above, the communication environment compatible data added in the response packet is:
The communication environment measurement data measured at the receiving terminal, the communication environment measurement data is added to the response packet, returned to the transmitting terminal, the transmitting terminal,
Based on the communication environment measurement data in the response packet returned from the receiving terminal, an optimal environment-adaptive communication parameter is set under the environment based on the communication environment measurement data, and the transmission should be performed according to the set environment-adaptive communication parameter. A data packet is transmitted to the receiving terminal.

The communication environment-compatible data added in the response packet is an optimum environment-adaptive communication parameter selected based on communication environment measurement data measured on the receiving terminal side. An environment-adaptive communication parameter is added to the response packet and returned to the transmitting terminal. The transmitting terminal transmits the optimal environment-adaptive communication in the response packet returned from the receiving terminal. The data packet to be transmitted is transmitted to the receiving terminal by a parameter.

Further, the environment-adaptive communication parameter is a communication rate indicating a data communication speed, and is set so that communication can be performed at a plurality of communication rates within a certain range. An optimal communication rate adapted to the environment at the time of the location where the side terminal exists is selected, and the data packet to be transmitted is transmitted at the selected communication rate.

Further, the environment-adaptive communication parameters are as follows:
Error correction coding strength, it is possible to set a plurality of levels of error correction coding strength in a certain range, the optimal error correction coding strength adapted to the environment at that time of the location where the receiving terminal is present Is selected, and the data packet to be transmitted is transmitted according to the selected error correction coding strength.

Further, the transmission request packet is an RTS packet, and a response packet to the RTS packet is a CTS packet.

A response packet indicating the reception state returned from the receiving terminal after transmitting the data packet is an AC packet.
It is characterized by being a K packet or a NAK packet.

As described above, according to the first embodiment of the present invention, before transmitting a data packet to be transmitted from the transmitting terminal to the receiving terminal, the transmitting terminal mainly establishes a wireless transmission path. A transmission request packet (RTS) with the receiving terminal
Packet and a response packet (CTS packet) thereof are applied to a communication method in which a communication procedure is set.

In such a communication system, the receiving terminal measures the communication environment status at the location where the receiving terminal is located, and uses the data obtained thereby as communication environment compatible data, and the communication environment compatible data is used as the data. It is added to the response packet and returned to the transmitting terminal. Then, based on the communication environment corresponding data in the response packet returned from the receiving terminal, the transmitting terminal originally uses the optimum environment-adaptive communication parameter adapted to the communication environment of the receiving terminal at that time. The data packet to be sent is transmitted to the receiving terminal.

That is, the receiving terminal measures an S / N ratio and a delay spread (described later) as communication environment conditions, and performs communication using environment-adaptive communication parameters corresponding to the S / N ratio and the delay spread.

The environment-adaptive communication parameters referred to here are, specifically, a communication rate and an error coding strength. For example, if the communication environment of the receiving terminal is poor, communication is performed at a low communication rate. If the communication environment of the receiving terminal is good, communication at a high communication rate is performed,
Communication is performed at an appropriate communication rate according to the environment. As a result, communication can be performed at an optimum communication rate according to the communication environment of the location where the receiving terminal exists, so that the occurrence of an error rate can be reduced and high-quality communication can be performed.

According to the present invention, if the communication environment is poor by performing such communication, the communication rate itself can be kept low. However, if data transmission is performed at a higher communication rate than this. Even if this is the case, the error rate at the receiving terminal is high, and high throughput cannot be obtained.
On the other hand, by performing data transmission at a low communication rate that is optimized under the environment at that time, the error rate at the receiving terminal is reduced even if the communication speed itself is low, and eventually the transmission rate is reduced. The system throughput can be increased, and efficient and high-quality communication can be performed.

Similarly, if the communication environment of the receiving terminal is poor, communication is performed with a high error coding strength, and if the communication environment of the receiving terminal is good, communication is performed with a low error coding strength. In this way, it is also possible to perform communication with an appropriate error coding strength according to the environment, and thereby it is possible to reduce the occurrence of an error rate at the receiving terminal. Throughput can be increased, and efficient and high-quality communication can be performed.

The communication environment compatible data added in the response packet may be the communication environment measurement data (S / N ratio, delay spread, etc.) itself, or the communication environment measurement data (S / N ratio data). And delay spread, etc.) to determine the optimal environment-adaptive communication parameters (communication rate and error correction coding strength) in that environment, and put the obtained communication rate and error correction coding strength in the response packet. It may be added and returned to the transmitting terminal.

When the communication environment measurement data itself, such as the S / N ratio and delay spread, is added to the response packet and returned to the transmitting terminal, the receiving terminal uses
Since it is only necessary to measure the communication environment measurement data such as the / N ratio and the delay spread, and to add the measured communication environment measurement data to the response packet and return it, the processing load on the receiving terminal can be reduced.

On the other hand, in the latter method, a communication rate and an error correction coding strength are obtained from communication environment measurement data such as an S / N ratio and a delay spread at a receiving terminal, and the obtained communication rate is obtained. And the error correction coding strength is added to the response packet and returned to the transmitting terminal, so that the transmitting terminal transmits the data packet using the transmitted communication rate and error correction coding strength as they are. Therefore, the processing load on the transmitting terminal can be reduced.

The present invention is one of the existing communication protocols.
Using the RTS and CTS functions, the communication environment-compatible data (communication environment measurement data itself or the communication rate or error correction coding strength obtained based on the communication environment measurement data) is added to the CTS packet. To return to the sending terminal. As described above, since the present invention can be realized by using the existing communication protocol, it is not necessary to largely change the entire communication system.

Further, according to a second aspect of the present invention, when the transmitting terminal performs continuous data packet transmission to the receiving terminal, after transmitting one or more data packets, the receiving state of the packet data is determined. This is suitable for a communication system in which a response packet indicating the following is received from the receiving terminal and the next data packet is transmitted as the next transmission procedure, for example. Also in such a communication method, the communication packet corresponding to the communication environment is added to the response packet and returned to the transmission side, and the transmission side can perform communication with the environment-adaptive communication parameters according to the data.

That is, when the transmitting terminal performs data communication with the receiving terminal, the transmitting terminal receives the ACK packet as a response packet from the receiving terminal and transmits the data packet. The communication environment response data is added to the ACK packet, and the packet is returned. When a data packet is continuously transmitted from the transmitting terminal, the receiving terminal receiving the data packet adds the above communication environment compatible data to the ACK packet returned between one data packet and a subsequent data packet. I do.

As described above, when a data packet is continuously transmitted from the transmitting terminal, the data corresponding to the communication environment is added to the ACK packet returned from the receiving terminal to the transmitting terminal and transmitted each time. Can be transmitted at a communication rate and error correction coding strength optimized for each data packet. Also, if the receiving side terminal is set to return a NAK packet when the receiving side cannot perform normal reception, this N
Communication environment compatible data may be added to the AK packet. The NAK packet is a packet for requesting retransmission of the data packet. When the NAK packet is received by the transmitting terminal, the NAK packet retransmits the data packet to the receiving terminal.

Also in this case, an ACK packet or NAK packet return function as one of the existing communication protocols is used, and the ACK packet or NAK packet includes the communication environment compatible data (the communication environment measurement data itself or the communication environment). The communication rate and the error correction coding strength obtained based on the environment measurement data are added back to the transmitting terminal. As described above, since the present invention can be realized by using the existing communication protocol, it is not necessary to largely change the entire communication system.

[0040]

Embodiments of the present invention will be described below with reference to the drawings. The embodiment will be described separately for the first embodiment and the second embodiment.

[First Embodiment] FIG. 1 is a schematic block diagram for explaining an embodiment of a packet communication device in a wireless LAN according to the present invention, and a packet communication device 1 in a wireless LAN according to the present invention. Is roughly divided into
The communication control unit 30 includes a signal transmission / reception unit 10, a transmission / reception data generation unit 20, and a communication control unit 30, to which a personal computer 2, for example, is connected as an information processing device. The combination of the packet communication device 1 and the personal computer 2 is referred to as a terminal.

The packet communication device 1 shown in FIG.
Is suitable for a communication system conforming to IEEE 802.11, and in this embodiment, it is assumed that communication is performed by a spread spectrum communication method. However, in FIG. 1, a spreading code generator and a spreading / despreading device are used.
Components such as those necessary for spread spectrum communication and components that are not particularly required for describing the present invention are not shown.

The signal transmission / reception section 10 has a demodulation section 11 on the data reception side and a modulation section 12 on the data transmission side. The demodulation unit 11 is connected to the reception antenna 3 and the modulation unit 12 is connected to the transmission antenna 4. Here, an example is shown in which antennas are separately provided for the reception system and the transmission system, but one antenna may be shared.

The transmission / reception data generation unit 20 has an A / D conversion unit 21 and a decryption unit 22 on the data reception side.
On the data transmission side, an encoding unit 23, a D / A conversion unit 24
And a communication environment status measuring unit 25 in addition. Further, the encoding unit 23 includes an error correction encoding strength variable unit 231 and a communication rate variable unit 232.

The communication environment condition measuring section 25 measures the communication environment condition at the place where the personal computer 2 exists, and the environment condition to be measured is, for example, S / N.
These are ratio and delay spread, and these are called communication environment measurement data. This delay spread is used as an amount indicating the spread of the signal propagation delay time until the signal from the transmitting terminal reaches the receiving terminal, and varies depending on the communication environment. This delay spread is described on pages 10 to 14 of the mobile communication handbook issued by Ohmsha.

The communication control unit 30 is interposed between the personal computer 2 and the transmission / reception data generation unit 20 to transmit and receive data between the personal computer 2 and the transmission / reception data generation unit 20 and to perform various processes (such as The data extracting unit 3 extracts various data from the transmitted packet.
1, the data transmission system has a packet data generation unit 32 for packetizing data from the personal computer 2,
In addition, communication parameter control for controlling the error correction coding strength variable unit 231 and the communication rate variable unit 232 provided in the communication data generation unit 20 according to the communication environment of another terminal (receiving terminal). It has a part 33. The communication parameter control unit 33, the error correction coding strength setting unit 231 and the communication rate variable unit 232 are collectively referred to as an environment-adaptive communication parameter setting unit.

When transmitting a data packet to a receiving terminal, the packet communication device 1 of the present invention sends a data packet to be transmitted to the receiving terminal by using an optimal environment-adaptive communication parameter suitable for the communication environment of the receiving terminal. To do.
The environment-adaptive communication parameter is, specifically, a communication rate or an error correction coding strength that means a communication speed, and one or both of them are optimal values suitable for the communication environment of the receiving terminal. To transmit data packets.

As for the communication rate, an optimum communication rate can be set from a plurality of communication rates according to the communication environment. Specifically, the highest communication rate is 12 Mbps, and the lowest communication rate is 1 Mbps.
ps, and the interval is divided into, for example, five communication rates (total of seven steps), and can be set to any one of the communication rates.

It is to be noted that the lowest communication rate IM
The communication rate of bps is stepped up to a first communication rate R1, a second communication rate R2, a third communication rate R3, and the highest communication rate 1
Let 2 Mbps be the seventh communication rate R7. The above-described communication rate variable unit 232 sets the communication rate to the first to seventh communication rates.
Is set to one of the communication rates R1 to R7.

Similarly, the error correction code strengths are, for example, seven levels of error correction code strengths from a first error correction code strength E1 (weakest) to a seventh error correction coding strength E5 (strongest). Can be set, and an optimum error correction code strength can be set according to the communication environment. The above-described error correction coding strength variable section 231 sets the error correction coding strength to any one of the first to seventh error correction coding strengths E1 to E7.

The packet communication device 1 shown in FIG.
Performs communication by the spread spectrum communication method as described above, and its basic processing is the same as that of the conventional one. Therefore, the decoding process and the encoding process in the decoding unit 22 and the encoding unit 23 of the transmission / reception data generation unit 20, and the processing of the demodulation unit 11 and the modulation unit 12 in the signal transmission / reception unit 10 are the same as those of the conventional communication device. Since the configuration is the same, the illustration of the detailed configuration and the processing contents are omitted here.

Further, as described above, the present invention relates to the IEEE
It is suitable for a communication system based on 802.11, and one of the protocols of IEEE 802.11 includes:
RTS (Request to Send) and CTS
A communication procedure is set in which a packet called (Clear to Send: transmission path opened) is sent and received, and then data to be sent is sent.

This is, as shown in FIG.
1 sends a request to send data by means of an RTS packet as a transmission request packet, the RTS
The packet is received by the other terminals T2, T3, T4 and the RTS
Only the terminal specified by the address of the destination terminal in the packet (hereinafter referred to as terminal T4) has the CT as the response packet.
Send the S packet back to terminal T1.

As described above, first, before the data packet to be sent, the RTS packet is first sent from the transmitting terminal T1. When the CTS packet is returned from the receiving terminal T4, the transmitting terminal T1 returns to the original terminal. The data packet to be sent is sent to the receiving terminal T4. R
The transmission / reception of the TS / CTS packet is mainly for securing the right to occupy the wireless transmission path, and thereafter, the transmitting terminal and the receiving terminal occupy the wireless transmission path for a certain period of time. , Data can be exchanged.

Further, by adopting such a communication method by transmitting and receiving the RTS / CTS packet, the occupation time can be minimized without wasting the radio transmission line. That is, a data packet containing data to be transmitted generally has a large data amount and a long packet length. Therefore, when a data packet having a long packet length is transmitted from the beginning and the communication environment of the receiving terminal is not good and the data cannot be normally received, the wireless transmission path may be wastefully occupied for a long time.

On the other hand, the RTS / CTS packet is a packet whose packet length is very short as compared with the data packet to be transmitted, and the influence on the radio transmission system is minimized even if the transmission / reception fails. be able to. Therefore, before confirming whether data communication can be performed normally by transmitting / receiving these RTS / CTS packets prior to the data to be transmitted, the data packet to be transmitted is transmitted.
Useless occupation of the wireless transmission path can be prevented.

FIG. 3 is a diagram showing the data structure of the RTS packet. The header D1 used for synchronizing the transmission / reception data generation unit 20 shown in FIG. 1 and various packets (RTS packet, CTS packet, other Packet type data D2 for discriminating packets, a series of packet transmission / reception (the transmitting terminal transmits an RTS packet,
The receiving terminal returns a CTS packet, and thereafter, the transmitting terminal transmits data to be transmitted, and wireless transmission indicating the occupation time of the wireless transmission path necessary until the receiving terminal receives the data). The road occupancy time data D3, the address D4 of the destination terminal (the terminal T4 in the example of FIG. 2), the address D5 of the source terminal (the terminal T1 in the example of FIG. 2), and the source terminal from the packet type data D2 of these various data. It comprises an error detection additional bit D6 for detecting whether each data up to the address D5 has an error.

FIG. 4 shows the data structure of a CTS packet. FIG. 4A shows a conventional CTS packet, and FIG. 4B shows a CTS packet used in the embodiment of the present invention. The conventional CTS packet shown in FIG. 2A is basically the same as the RTS packet shown in FIG.
12, occupancy time data D13, destination terminal address D14, error detection additional bit D15, and the like.

In addition, C used in the embodiment of the present invention
The TS packet, as shown in FIG.
Almost similarly to the S packet, a header D11, packet type data D12, wireless transmission path occupancy time data D13, destination terminal address D14, error detection additional bit D15
Is provided, and in addition, the communication environment status measuring unit 25 described above is provided.
In this configuration, data D16 obtained by measuring the environment (hereinafter, referred to as communication environment-compatible data) is added.

The data corresponding to the communication environment is the communication environment measurement data (S / N ratio or delay spread) itself measured by the communication environment condition measuring section 25 or the environment adaptation obtained based on the communication environment measurement data. Communication parameters (communication rate and error coding strength). Either the communication environment measurement data or the environment-adaptive communication parameter obtained based on the communication environment measurement data is added to the CTS packet as the communication environment corresponding data D16. An example in which the measurement data itself is added to the CTS packet as the communication environment data D16 will be described.

In such a configuration, the processing procedure of the embodiment of the present invention will be described next with reference to the flowcharts of FIGS. In the present invention, the communication rate and the error correction coding strength are considered as the environment-adaptive communication parameters. However, in the flowcharts shown in FIGS. Is shown.

Here, an example in which the terminal T1 performs data communication with the terminal T4 as shown in FIG. 2 will be described. The terminals T1, T shown in FIG.
2, T3 and T4 are each composed of a personal computer 2 and a packet communication device 1 connected thereto, as shown in FIG.

On the terminal T1 side, first, the communication control unit 30 receives data from the personal computer 2 (step s1),
The transmission / reception data generation unit 2 notifies that no other terminal is communicating.
Confirm through 0 (step s2). Then, the RTS packet is sent to the transmission / reception data generator 20. Thereby, the transmission / reception data generation unit 20 processes the RTS packet using the safest transfer rate (for example, 1 Mbps) and drives the signal transmission / reception unit 10 (step s).
3). As a result, the RTS packet is transmitted from the antenna 4 (step s4), and the terminal T1 enters a state of waiting for the return of the CTS packet from the destination terminal (step s5).

On the other hand, on the other terminals T2, T3, T4,
As shown in FIG. 6, in a packet reception waiting state (step s11), when an RTS packet is received in this state (step s12), a destination terminal address in the RTS packet is read (step s13) and its own address is read. It is determined whether or not (step s14).

If it is not your own address,
The process returns to step s11, and enters a packet reception waiting state.
If it is determined that the address is its own address, the process proceeds to step s15 and subsequent steps. In this case, since the communication partner of the terminal T1 is the terminal T4, only the terminal T4 performs the processing after step s15.

The terminal T4 acquires the communication environment measurement data measured by the communication environment condition measurement unit 25 provided in the transmission / reception data generation unit 20 of its own packet communication device 1 (step s15), and FIG. A CTS packet as shown in (1) is generated (step s16).

That is, as shown in FIG. 4 (b), a CTS packet to which the communication environment compatible data D16 is added in addition to the various data constituting the conventional CTS packet is generated. In this case, the communication environment compatible data D16 is
This is communication environment measurement data, such as the S / N ratio and delay spread based on the communication environment at the location where the terminal T4 is located.

When terminal T4 returns the CTS packet to terminal T1 (step s17), it returns to the packet receiving state (step s11).

Thus, the transmitting terminal (terminal T1)
When the CTS packet is returned to the terminal T1 from the receiving terminal (terminal T4), which is the communication partner of the terminal, the description returns to the flowchart of FIG.
The S packet is received by the antenna 3 (step s6), demodulated by the demodulation unit 11, A / D converted by the A / D conversion unit 21, then decoded by the decoding unit 22, and sent to the communication control unit 30. .

As a result, the communication parameter control unit 33 in the communication control unit 30 sets the optimal environment-adaptive communication parameters based on the communication environment measurement data added in the CTS packet (step s7). Here, an optimal communication rate is set as an optimal environment-adaptive communication parameter. The setting of the optimum communication rate is performed by the communication parameter control unit 33 variably controlling the communication rate variable unit 232.

The communication rate of the packet communication device 1 according to the present invention ranges from 1 Mbps to 12 Mbps as described above.
bps, the first to seventh communication rates R1 to R7
Can be set.

FIG. 7 is a diagram showing an example of a table for determining which communication rate among the first to seventh communication rates R1 to R7 is optimum with respect to the aforementioned communication environment measurement data. The communication parameter control unit 33 obtains an optimum communication rate for the communication environment measurement data from the table. The communication environment measurement data used here is an S / N ratio and a delay spread. The S / N ratio is plotted on the horizontal axis, and the delay spread is plotted on the vertical axis. .

For example, if the value of S / N is x5 and the value of delay spread is y1, the second communication rate R2 closest to point p1 on the two-dimensional coordinates is selected. That is, it can be said that the second communication rate R2 is an optimum communication rate in the communication environment of the terminal T4 when the terminal T1 communicates with the terminal T4.

In this case, the communication parameter control section 33 controls the communication rate variable section 232 in this case, so that setting is made such that communication at the second communication rate R2 is performed. When the communication rate is set in this way, data packets that should be sent are sent at the set communication rate (step s8). Therefore,
In this case, the data that should be sent is the second communication rate R2
Will be sent by This second communication rate R2 is:
Under the environment of the terminal T4, this is an appropriate communication rate with the lowest error rate.

That is, in this example, although the communication rate itself is a low communication rate, even if data transmission is performed at a higher communication rate, the error rate at the terminal T4, which is the receiving terminal, is reduced. High, and a good communication state cannot be obtained. On the other hand, by performing data transmission at the second communication rate R2 that is optimized in the environment at that time, the error rate on the receiving side is reduced even though the communication speed itself is low. The throughput of the transmission system can be increased.

In the above description, the communication rate is the optimal environment-adaptive communication parameter set in accordance with the communication environment measurement data. It is also possible to set a strong error correction coding strength. This will be described below.

In this case, as described above, the error correction coding strength is set to, for example, the first error correction coding strength E1.
Seven levels of error correction coding strength are set from (weakest) to seventh error correction coding strength E7 (strongest), and an optimum error correction coding strength is set according to communication environment measurement data. . Also in this case, similar to the communication rate described above,
A table capable of setting the optimum error correction coding strength for the communication environment measurement data is created in advance.

FIG. 8 shows an example of this table. FIG. 8 is a table showing the relationship between the first to seventh error correction coding intensities E1 to E7 for the communication environment measurement data. From this table, the error correction coding intensities for the communication environment measurement data can be obtained.

The environmental data used here is the S / N ratio and delay spread, the S / N ratio is plotted on the horizontal axis and the delay spread is plotted on the vertical axis, as in FIG. Find an appropriate error correction code strength. For example, S /
Assuming that the value of N is x5 and the value of the delay spread is y1, the first error correction coding strength E1 closest to the point p1 on the two-dimensional coordinates is obtained. That is, it can be said that the first error correction coding strength E1 is the optimum error correction coding strength in the communication environment of the terminal T4 when the terminal T1 communicates with the terminal T4.

Thus, in this case, the error correction coding strength variable section 231 is controlled by the communication parameter control section 33, and setting is made such that communication is performed at the first error correction coding strength E1. When the error correction coding strength is set in this way, the data packet to be transmitted is transmitted at the set first error correction coding strength E1. This first error correction coding strength E1
Is the optimum error correction coding strength under the environment of the terminal T4.

As described above, by setting an appropriate error correction coding strength according to the environment, optimal communication can be performed in the environment at that time, as in the case of selecting an optimal communication rate.

It is to be noted that a communication rate and an error correction coding strength optimized according to the environment can be used in combination. For example, in the above example, the value of S / N is x5
If the value of the delay spread is y1, the second communication rate R2 and the first error correction coding strength E1 closest to the point p1 on the two-dimensional coordinates will be selected. As described above, by performing data communication with the second communication rate R2 and the first error correction coding strength E1 which are optimal in the environment at that time, an optimal communication state further adapted to the environment is obtained. Can be

[Second Embodiment] In the second embodiment, after transmitting a data packet from a transmitting terminal to a receiving terminal, a response packet (ACK) indicating that the packet has been normally received is transmitted. (Referred to as a packet) from the receiving terminal and transmit the next data packet. In this case, first, a communication method in which a communication procedure for transmitting / receiving the RTS / CTS packet described in the first embodiment may be used, but the present invention is not limited to this. The processing for setting the optimum environment-adaptive communication parameters based on the communication environment measurement data is the same as in the first embodiment. Less than,
A second embodiment will be described.

When a data packet is continuously transmitted from a certain terminal (referred to as terminal T1) to a certain terminal (referred to as terminal T4), data packets are successively transmitted from the transmitting terminal, but are received. The receiving terminal returns an ACK packet to the terminal T1 between one data packet and a subsequent data packet. This ACK packet is a packet issued by the receiving terminal in order to notify the transmitting terminal that the data packet has been normally received by the receiving terminal. Retransmit the data packet that was not received.

FIG. 9 is a diagram showing this state. When the first data packet DP1 is transmitted from the transmitting terminal and is normally received by the receiving terminal, the first data packet DP1 is transmitted from the receiving terminal to the first data packet DP1.
ACK packet AP1 is returned. This first ACK
When the transmitting terminal receives the packet AP1, a second data packet DP2 is transmitted from the transmitting terminal, and when it is normally received by the receiving terminal, a second ACK packet AP2 is returned. Each time the receiving terminal receives one data packet, it returns an ACK packet to the transmitting terminal between the receiving terminal and a subsequent data packet.

In each of these ACK packets, the first
The same communication environment compatible data as described in the embodiment can be added. FIG. 10 is a diagram schematically showing a data configuration of an ACK packet according to the second embodiment. This ACK packet can be configured in the same manner as the CTS packet (see FIG. 4B) used in the first embodiment described above, and includes a header D21, packet type data D22, and radio transmission path occupation time data D23. In addition to the address D24 of the destination terminal and the additional bit D25 for error detection, communication environment compatible data D26 is added.

As described in the first embodiment, the communication environment corresponding data D26 measured here is the communication environment measurement data (S / N ratio or delay spread) or the communication environment measurement data. Environment-adaptive communication parameters (communication rate and error correction coding strength) set based on The method of setting the communication rate and the error correction coding strength based on the measured communication environment measurement data has already been described, and a description thereof will be omitted.

As described above, when data packets are continuously transmitted, the AC transmitted from the receiving terminal to the transmitting terminal is
By transmitting the communication environment-compatible data in the K packet, each data packet is transmitted at a communication rate and an error correction coding strength optimized for each data packet.

Note that also in the second embodiment,
It is also possible to use a combination of the communication rate and error correction coding strength optimized according to the environment, and by performing communication with the optimum communication rate and error correction coding strength under the environment at that time, An optimal communication state adapted to the environment can be obtained.

The present invention is not limited to the above-described embodiment, but can be variously modified without departing from the gist of the present invention.

For example, in each of the above-described embodiments, the communication environment condition is measured at the receiving terminal, and the communication environment measurement data (S / N ratio or delay spread) itself as the measurement result is included in the CTS packet or ACK. The packet is added as communication environment-compatible data D16 or D26 in the packet and returned to the transmitting terminal, and the transmitting terminal determines the optimal environment-adaptive communication parameters (communication rate and error correction coding strength) based on the measurement result. A data packet that should be sent to the receiving terminal is transmitted according to the obtained environment-adaptive communication parameter obtained from a table prepared in advance.

However, the present invention is not limited to this. The receiving terminal measures the communication environment measurement data, and based on the S / N ratio and the delay spread as the measurement result, optimizes the environment adaptation communication parameters (communication parameters). Rate, error correction coding strength) from the table, and the obtained environment-adaptive communication parameters are stored in the CTS packet or in the AC.
The data packet to be transmitted to the receiving terminal is transmitted to the transmitting terminal by adding it as communication environment data D16 or D26 to the transmitting terminal by the environment-adaptive communication parameters transmitted from the receiving terminal. You may make it transmit.

For example, as communication environment correspondence data D16 in the CTS packet returned from the receiving terminal,
Assuming that data indicating the second communication rate R2 has been written, in the transmitting terminal that has received the data, the communication parameter control unit 33 provided in the communication control unit 30 converts the data indicating the second communication rate R2. The read instruction is issued to the variable communication rate unit 232 to set the second communication rate R2. Thus, the data packet sent from the transmitting terminal to the receiving terminal is transmitted at the second communication rate R2.

As described above, if data indicating the environment-adaptive communication parameter itself is included in the CTS packet returned from the receiving terminal, the transmitting terminal receiving the CTS packet transmits the communication environment measurement data. It is not necessary to perform the process of obtaining the optimum environment-adaptive communication parameters (communication rate and error correction coding strength) from the table based on the above, so that the processing load on the transmitting terminal can be reduced.

In each of the above embodiments,
The maximum communication rate is 12 Mbps, the minimum is 1 Mbps, and the communication rate is set in 5 steps (7 steps in total) between them. However, the present invention is not limited to this. The stages allow various settings to be made as much as possible according to the system to be applied. In addition, similarly, various settings can be made for the error correction coding strength as much as possible according to the system to which the error correction coding is applied.

Further, in the second embodiment, an example has been described in which an ACK packet is used as a response packet and communication environment compatible data is added to the ACK packet. However, this is not limited to the ACK packet. Instead, for example, if the receiving terminal fails to receive data normally, the receiving terminal sends a NAK (Negati
If an acknowledgment packet is sent back, it is possible to add communication environment compatible data also in the NAK packet.

The processing program for performing the packet communication processing of the present invention described above can be recorded on a recording medium such as a floppy disk, an optical disk, or a hard disk. The present invention also includes the recording medium. Further, the processing program may be obtained from a network.

[0098]

As described above, according to the present invention,
Before the transmission of the data packet that should be sent from the transmitting terminal to the receiving terminal, a communication procedure is set so that a transmission request packet and a response packet to it are exchanged between the transmitting terminal and the receiving terminal. In the communication method, the receiving terminal measures the communication environment status at the location where the receiving terminal is located, and uses the data obtained thereby as communication environment compatible data, and stores the communication environment compatible data in the response packet. It is added back to the transmitting terminal. Then, based on the data obtained by measuring the communication environment state in the response packet returned from the receiving terminal, the transmitting terminal determines an optimal environment suitable for the communication environment of the receiving terminal at that time. Data packets that should be sent are transmitted to the destination terminal by the adaptive communication parameters.

That is, the S / N ratio and delay spread are measured as the communication environment status of the receiving terminal, and communication is performed using environment-adaptive communication parameters corresponding to the S / N ratio and delay spread. The environment-adaptive communication parameters here are, specifically, a communication rate indicating the communication speed and an error correction coding strength. For example, if the communication environment of the receiving terminal is poor, communication at a low communication rate is performed. Is performed, and if the communication environment of the receiving terminal is good, communication is performed at an appropriate communication rate according to the environment, such as performing communication at a high communication rate. As a result, communication can be performed at the optimum communication rate according to the communication environment of the location where the receiving terminal is located, so that the occurrence of an error rate can be reduced, and in the environment at that time, high efficiency and high quality can be achieved. Communication is possible.

Similarly, if the communication environment of the destination terminal is poor, communication is performed with a higher error correction coding strength, and if the communication environment of the destination terminal is good, the communication is performed with a lower error correction coding strength. It is also possible to perform communication with an appropriate error correction coding strength according to the environment,
This also makes it possible to reduce the occurrence of an error rate at the receiving terminal, thereby enabling efficient and high-quality communication under the environment at that time.

Further, the communication rate and the error correction coding strength can be used in combination, and by performing data communication at the optimum communication rate and error correction coding strength in the environment at that time, the environment can be further improved. An adapted, efficient and high-quality communication letter is made possible.

The present invention is one of the existing communication protocols.
Utilizing the RTS and CTS functions, the communication environment-compatible data is added to the CTS packet and returned to the transmitting terminal. As described above, since the present invention can be realized by using the existing communication protocol, it is not necessary to largely change the entire communication system.

Further, according to the present invention, after transmitting a data packet, an ACK packet or a NAK packet is received from the receiving terminal as a response packet indicating the reception state of the packet, and the data packet is transmitted as the next transmission procedure. It can be applied to various communication systems. In such a communication system, the communication environment-compatible data described above is added to a response packet (ACK packet or NAK packet). As a result, transmission can be performed at a communication rate and error correction coding strength optimized for each data packet, and communication at an optimum communication rate according to the communication environment at that time can be performed for each data packet. I can do it.

As described above, according to the present invention, communication can be performed using the optimum environment-adaptive communication parameter according to the communication environment at that time, and thus the terminal exists on a mobile object such as an automobile whose communication environment changes every moment. This is particularly effective in such cases.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an embodiment of a packet communication device in a wireless LAN according to the present invention.

FIG. 2 is a diagram illustrating exchange of an RTS / CTS packet, which is one of the IEEE 802.11 protocols.

FIG. 3 is a diagram schematically illustrating a configuration of an RTS packet.

4A and 4B are diagrams schematically illustrating a configuration of a CTS packet, FIG. 4A schematically illustrating a configuration of a conventional CTS packet, and FIG. 4B schematically illustrating a configuration of a CTS packet according to the present invention; FIG.

FIG. 5 is a flowchart illustrating a processing procedure according to an embodiment of the present invention, and is a flowchart illustrating a processing procedure of a transmitting terminal.

FIG. 6 is a flowchart illustrating a processing procedure according to an embodiment of the present invention, and is a flowchart illustrating a processing procedure of a terminal other than the transmitting terminal.

FIG. 7 is a diagram showing an example of a table for selecting an optimum communication rate based on communication environment measurement data (S / N ratio and delay spread).

FIG. 8 is a diagram showing an example of a table for selecting an optimum error correction coding strength based on communication environment measurement data (S / N ratio and delay spread).

FIG. 9 is a diagram illustrating continuous data packet transmission using an ACK packet according to the second embodiment of the present invention.

FIG. 10 is a diagram schematically illustrating a configuration of an ACK packet according to the second embodiment.

[Explanation of symbols]

 Reference Signs List 1 packet communication device 2 personal computer 3 reception antenna 4 transmission antenna 10 signal transmission / reception device 11 demodulation unit 12 modulation unit 20 transmission / reception data generation unit 22 decoding unit 23 encoding unit 231 error correction coding strength variable unit 232 communication rate Variable unit 25 Communication environment status measurement unit 30 Communication control unit 31 Data extraction unit 32 Packet generation unit 33 Communication parameter control unit T1 Transmitting terminal T4 Receiving terminal D16, D26 Communication environment corresponding data R1 to R7 First to seventh communications Rate E1 to E7 First to seventh error correction coding strength

Continued on front page F term (reference) 5K014 AA02 BA05 DA02 FA11 5K033 AA07 CB03 CB04 CC01 DA17 DB09 DB16 EA06 EC01 5K034 AA05 EE01 EE03 EE11 HH01 HH02 MM01 NN13 NN26 5K067 AA23 BB21 CC08 DD11 DD43 DD45

Claims (19)

[Claims] 1. A packet communication method in wireless communication in which data to be transmitted is packetized using a wireless medium such as radio waves or light to perform mutual communication, wherein a transmitting terminal transmits the data to be transmitted to a receiving terminal. Before transmitting a packet, a transmission request packet is sent to the receiving terminal mainly to secure a wireless transmission path, and if the received transmission request packet can be received at the receiving terminal, reception is possible. In the packet communication method in wireless communication in which a communication procedure for returning a response packet indicating that the reception terminal is present, the receiving terminal measures a communication environment condition at a location where the receiving terminal is present, and obtains the The received data is used as communication environment compatible data, the communication environment compatible data is added to the response packet, and the response packet is returned to the transmitting terminal. The terminal, based on the communication environment corresponding data in the response packet returned from the receiving terminal, based on the optimum environment-adaptive communication parameters adapted to the communication environment at that time of the receiving terminal, the data to be transmitted. A packet communication method in wireless communication, wherein a packet is transmitted to the receiving terminal. 2. The communication environment compatible data added in the response packet is communication environment measurement data measured by the receiving terminal, and the communication environment measurement data is added to the response packet to Returning to the transmitting terminal, the transmitting terminal sets an optimal environment-adaptive communication parameter under the environment based on the communication environment measurement data in the response packet returned from the receiving terminal. 2. The packet communication method in wireless communication according to claim 1, wherein the data packet to be transmitted is transmitted to the receiving terminal according to the set environment-adaptive communication parameter. 3. The communication environment-compatible data added in the response packet is an optimum environment-adaptive communication parameter selected based on communication environment measurement data measured on the receiving terminal side. An environment-adaptive communication parameter is added to the response packet and returned to the transmitting terminal. The transmitting terminal transmits the optimal environment-adaptive communication in the response packet returned from the receiving terminal. 2. The packet communication method in wireless communication according to claim 1, wherein the data packet to be transmitted is transmitted to the receiving terminal by a parameter. 4. The environment-adaptive communication parameter is a communication rate indicating a data communication speed, and is set so as to enable communication at a plurality of communication rates within a certain range. The optimal communication rate adapted to the environment at that time in the place where the side terminal exists is selected,
4. The packet communication method in wireless communication according to claim 1, wherein the transmission of the data packet to be transmitted is performed at the selected communication rate. 5. The environment-adaptive communication parameter is an error-correcting coding strength, and enables setting of a plurality of levels of error-correcting coding strength within a certain range. 4. The data packet to be transmitted is transmitted according to the selected error correction coding strength, the optimum error correction coding strength adapted to the environment at the time point being selected. 2. A packet communication method in wireless communication according to claim 1. 6. The transmission request packet is an RTS (Reques
t to Send) packet, and the response packet is CT
The packet communication method according to any one of claims 1 to 5, wherein the packet communication method is an S (Clear to Send) packet. 7. A packet communication method in wireless communication in which data to be transmitted is packetized using a wireless medium such as an electric wave or light to perform mutual communication, wherein a transmitting terminal transmits to a receiving terminal one or more. After transmitting a plurality of data packets, a packet communication method in wireless communication that receives a response packet indicating a reception state of the packet data from a receiving terminal and performs a next transmission procedure, wherein the receiving terminal transmits the packet data. The communication environment status at that time is measured each time it is received, and the data obtained thereby is used as communication environment compatible data, and this communication environment compatible data is added to the response packet and returned to the transmitting terminal. The transmitting terminal, based on the communication environment corresponding data in the response packet returned from the receiving terminal, The optimal environment adaptation communication parameters suitable for the communication environment at that time side terminal, a packet communication method in a radio communication, characterized in that the next data packet to be transmitted to the receiving terminal. 8. The communication environment compatible data added in the response packet is communication environment measurement data measured by the receiving terminal, and the communication environment measurement data is added to the response packet to Returning to the transmitting terminal, the transmitting terminal sets an optimal environment-adaptive communication parameter under the environment based on the communication environment measurement data in the response packet returned from the receiving terminal. 8. The packet communication method in wireless communication according to claim 7, wherein the data packet to be transmitted is transmitted to the receiving terminal according to the set environment-adaptive communication parameter. 9. The communication environment-compatible data added in the response packet is an optimum environment-adaptive communication parameter selected based on communication environment measurement data measured on the receiving terminal side. An environment-adaptive communication parameter is added to the response packet and returned to the transmitting terminal. The transmitting terminal transmits the optimal environment-adaptive communication in the response packet returned from the receiving terminal. 8. The packet communication method in wireless communication according to claim 7, wherein the data packet to be transmitted is transmitted to the receiving terminal by a parameter. 10. The environment-adaptive communication parameter is a communication rate indicating a data communication speed, and is set so as to enable communication at a plurality of communication rates within a certain range. 10. The data packet to be transmitted according to claim 7, wherein an optimum communication rate adapted to the current environment of the place where the side terminal exists is selected, and the data packet to be transmitted is transmitted according to the selected communication rate. A packet communication method in wireless communication according to any one of the preceding claims. 11. The environment-adaptive communication parameter is an error-correcting coding strength, and enables setting of a plurality of levels of error-correcting coding strength within a certain range. 10. The data packet to be transmitted is transmitted according to the selected error correction coding strength, the optimum error correction coding strength adapted to the environment at the time point being selected. 2. A packet communication method in wireless communication according to claim 1. 12. The response packet is an ACK (Acknow
ledgement) packet or NAK (Negative Acknowle)
12. A packet communication method in wireless communication according to claim 7, wherein the packet communication method is a dgement) packet. 13. A packet communication device in wireless communication for packetizing data to be transmitted using a wireless medium such as radio waves or light and performing mutual communication, wherein a transmitting terminal receives a response packet from a receiving terminal. In a packet communication device in wireless communication for transmitting a data packet, a transmission / reception data generation unit having a communication environment condition measuring means for measuring a communication environment condition at a place where the own terminal is present; It is possible to add the communication environment compatible data to the response packet and output the same, and when the communication environment compatible data in the response packet sent from another terminal to its own terminal is received, A communication control unit capable of setting an optimum environment-adaptive communication parameter suitable for the communication environment of the other terminal at that time When the own terminal is a receiving side, the communication environment state of the place where the own terminal exists is measured by the communication environment measuring means, and the data obtained thereby is used as communication environment compatible data, The communication environment compatible data is added to the response packet and returned to the transmitting terminal. If the own terminal is the transmitting side, the communication environment in the response packet returned from the receiving terminal is returned. Wireless communication, characterized in that the data packet to be transmitted is transmitted to the receiving terminal by an optimal environment-adaptive communication parameter adapted to a communication environment at that time of the receiving terminal based on the corresponding data. Packet communication device. 14. The communication environment compatible data added in the response packet is communication environment measurement data measured by the receiving terminal, and the communication environment measurement data is added to the response packet to Returning to the transmitting terminal, the transmitting terminal sets an optimal environment-adaptive communication parameter under the environment based on the communication environment measurement data in the response packet returned from the receiving terminal. 14. The packet communication device in wireless communication according to claim 13, wherein the data packet to be transmitted is transmitted to the receiving terminal according to the set environment-adaptive communication parameter. 15. The communication environment-compatible data added in the response packet is an optimum environment-adaptive communication parameter selected based on communication environment measurement data measured on the receiving terminal side. An environment-adaptive communication parameter is added to the response packet and returned to the transmitting terminal. The transmitting terminal transmits the optimal environment-adaptive communication in the response packet returned from the receiving terminal. 14. The data packet to be transmitted is transmitted to the receiving terminal by a parameter.
A packet communication device in wireless communication according to any one of the preceding claims. 16. The environment-adaptive communication parameter is a communication rate indicating a data communication speed, and is set so as to enable communication at a plurality of communication rates within a certain range. 16. The data packet to be transmitted according to claim 13, wherein an optimum communication rate adapted to the current environment of the place where the side terminal exists is selected, and the transmission of the data packet to be transmitted is performed according to the selected communication rate. A packet communication device in wireless communication according to any one of the preceding claims. 17. The environment-adaptive communication parameter is an error-correcting coding strength, and enables setting of a plurality of levels of error-correcting coding strength within a certain range. 16. The data packet to be transmitted is transmitted according to the selected error correction coding strength, the optimum error correction coding strength adapted to the environment at the time point being selected.
The packet communication device in wireless communication according to any one of the above. 18. The apparatus according to claim 13, wherein the response packet is a CTS (Clear to Send) packet for an RTS (Request to Send) packet transmitted from the transmitting terminal. A packet communication device in wireless communication according to claim 1. 19. The response packet indicates a reception state of a data packet transmitted from the transmitting terminal.
CK (Acknowledgement) packet or NAK (Negat)
18. A packet communication device for wireless communication according to claim 13, wherein the packet communication device is a ive acknowledgment packet.