JP2005260813A - Radio communication system, radio communication apparatus and method, recording medium, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently transmit data in accordance with reception power from an access point. <P>SOLUTION: Data (RSSI, for example) are received from an access point in step S1, and a reception power value is calculated from the received data in step S2. It is determined in step S3 whether or not the calculated reception power value is greater than a predetermined threshold and if it is determined that the reception power value is greater than the predetermined threshold, processing is advanced to step S4 to select an RTS non-transmission mode. If it is determined in step S3 that the calculated reception power value is smaller than the predetermined threshold, processing is advanced to step S6 to select an RTS transmission mode. Namely, if the reception power value is greater than the predetermined threshold, only a data packet is transmitted but if the reception power value is smaller than the predetermined threshold, RTS is transmitted, so that a band is ensured. The present invention may be applicable to a radio communication terminal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a wireless communication system, a wireless communication apparatus and method, a recording medium, and a program, and more particularly, for example, a wireless communication system capable of efficiently transmitting data according to received power from an access point, The present invention relates to a wireless communication apparatus and method, a recording medium, and a program.

  2. Description of the Related Art Conventionally, in a wireless communication system, a state where carriers cannot sense each other occurs due to the distance between terminals or the influence of an obstacle or the like existing between terminals. When such a situation occurs, each terminal simultaneously transmits a data packet toward the access point, resulting in frequent packet collisions. This is called the hidden terminal problem, and in the conventional technology, RTS (Request To Send) / CTS (Criteria) of IEEE (Institute of Electrical and Electronics Engineers) 802.11, which is standardizing wireless local area network (LAN) This problem is solved by using a packet called “Clear To Send”. Also, it is not essential to use RTS / CTS in a hidden terminal environment, and the problem may be solved without using RTS / CTS.

  By the way, in the case of using RTS / CTS in a hidden terminal environment, when RTSs transmitted from each terminal to the access point collide with each other, the access point receives RTS from a terminal with high reception power due to the capture effect. Receive preferentially. On the other hand, a terminal with low reception power repeats retransmission of RTS toward the access point. Therefore, a terminal with low reception power not only has a lower throughput than a terminal with high reception power, but also may collide with a packet by repeating retransmission of RTS and cause interference.

  Therefore, there is one that prevents interference due to RTS retransmission in an environment where a capture effect occurs (see, for example, Patent Document 1).

JP 2002-64505 A

  As described above, in the conventional technique, there are a case where RTS / CTS is used in a hidden terminal environment and a case where only a data packet is transmitted without using RTS / CTS. If RTS / CTS is not used, packet collision occurs at the access point, and if the received power at the access point of the terminal is smaller than that of the other terminal, the packet of the terminal is canceled and discarded. There was a problem that would be impossible.

  On the other hand, when the reception power of the terminal itself is large, data packets can be transmitted by using RTS, but there is a problem that throughput is deteriorated by the overhead of RTS.

  The present invention has been made in view of such a situation, and by switching between a mode using RTS / CTS and a mode not using RTS / CTS according to the value of received power from the access point, it is efficient. Data can be transmitted.

  The wireless communication system of the present invention is a wireless communication system including a wireless station and a terminal that wirelessly communicates with the wireless station. The wireless station includes a transmission unit that transmits a signal, and the terminal is transmitted from the wireless station. A calculation means for receiving an incoming signal and calculating a reception power value of the reception signal; a reception power value calculated by the calculation means; a comparison means for comparing a predetermined threshold; and a comparison result by the comparison means And a selection means for selecting a first mode for transmitting a transmission request packet for requesting data transmission or a second mode for not transmitting a transmission request packet.

  The selection unit selects the second mode when the received power value is determined to be larger than the threshold value as a result of the comparison by the comparing unit, and the first mode is selected when the received power value is determined to be smaller than the threshold value. Can be selected.

  The wireless communication apparatus of the present invention receives a signal transmitted from a wireless station, calculates a received power value of the received signal, a received power value calculated by the calculating means, and a predetermined threshold value And a selection unit for selecting a first mode for transmitting a transmission request packet for requesting data transmission or a second mode for not transmitting a transmission request packet based on the comparison result of the comparison unit It is characterized by providing.

  The selection unit selects the second mode when the received power value is determined to be larger than the threshold value as a result of the comparison by the comparing unit, and the first mode is selected when the received power value is determined to be smaller than the threshold value. Can be selected.

  The wireless communication method of the present invention receives a signal transmitted from a wireless station, calculates a received power value of the received signal, a received power value calculated by the processing of the calculating step, and a predetermined value. A first mode for transmitting a transmission request packet for requesting transmission of data, or a second mode for not transmitting a transmission request packet, based on a comparison step for comparing the threshold values and a comparison result by the processing of the comparison step And a selection step of selecting.

  The program recorded in the recording medium of the present invention receives a signal transmitted from a radio station, calculates a received power value of the received signal, and a received power value calculated by the process of the calculating step And a comparison step for comparing a predetermined threshold value, and a first mode for transmitting a transmission request packet for requesting data transmission based on a comparison result obtained by processing of the comparison step, or a transmission request packet is not transmitted. And a computer including a selection step of selecting a second mode.

  The program of the present invention receives a signal transmitted from a radio station, calculates a received power value of the received signal, a received power value calculated by the processing of the calculating step, and a predetermined threshold value And a first mode for transmitting a transmission request packet for requesting data transmission or a second mode for not transmitting a transmission request packet is selected based on the comparison result of the comparison step and the comparison result of the processing of the comparison step. The computer is caused to perform processing including a selection step.

  In the first aspect of the present invention, a signal is transmitted from a wireless station, a signal transmitted from the wireless station is received by a terminal, a received power value of the received signal is calculated, and the calculated received power value and The determined threshold values are compared, and based on the comparison result, a first mode for transmitting a transmission request packet for requesting transmission of data or a second mode for not transmitting a transmission request packet is selected.

  In the second aspect of the present invention, a signal transmitted from a radio station is received, a received power value of the received signal is calculated, a calculated received power value is compared with a predetermined threshold value, and a comparison result is obtained. Based on this, the first mode for transmitting a transmission request packet for requesting transmission of data or the second mode for not transmitting a transmission request packet is selected.

  According to the present invention, data can be transmitted efficiently. In particular, by switching between RTS / CTS mode and RTS / CTS mode according to the value of received power from the access point, it is possible to transmit data efficiently in a hidden terminal environment. At the same time, the throughput is improved.

  BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out the present invention will be described below. The correspondence relationship between the invention described in the specification and the embodiment is exemplified as follows. Although there is an embodiment which is described in the specification but is not described here as corresponding to the invention, it does not mean that the embodiment corresponds to the invention. It doesn't mean not. Conversely, even if an embodiment is described herein as corresponding to an invention, that means that the embodiment does not correspond to an invention other than the invention. Absent.

  Further, this description does not mean that all the inventions corresponding to the embodiments described in the specification are described. In other words, this description does not deny the existence of other inventions described in the specification, that is, the existence of inventions that will be filed in division in the future, or that appear and are added by amendments.

  The wireless communication system according to claim 1 (for example, the wireless communication system 1 in FIG. 1) includes a wireless station (for example, the access point 4 in FIG. 1) and a terminal that wirelessly communicates with the wireless station (for example, the terminal in FIG. 1). 2 and a terminal 3), wherein the wireless station includes a transmission means for transmitting a signal (for example, a received signal strength indication signal), and the terminal receives a signal transmitted from the wireless station. Then, a calculation means for calculating the received power value of the received signal (for example, the CPU 33 in FIG. 2 that executes the processing of step S1 and step S2 in FIG. 6), the received power value calculated by the calculation means, and a predetermined value are determined in advance. Based on the comparison result by the comparison means (for example, the CPU 33 in FIG. 2 that executes the processing of step S3 in FIG. 6) and the comparison result by the comparison means, the transmission request packet for requesting data transmission is transmitted. Selection means (for example, the CPU 33 in FIG. 2 that executes the processing in step S4 or step S6 in FIG. 6) that selects the first mode to be transmitted or the second mode in which the transmission request packet is not transmitted. And

  The wireless communication device according to claim 3 (for example, the terminal 2 and the terminal 3 in FIG. 1) is a signal (for example, a received signal strength indication signal) transmitted from a wireless station (for example, the access point 4 in FIG. 1). , And calculating the received power value of the received signal (for example, the CPU 33 of FIG. 2 that executes the processing of step S1 and step S2 of FIG. 6), the received power value calculated by the calculating unit, Comparison means for comparing a predetermined threshold value (for example, CPU 33 in FIG. 2 that executes the processing of step S3 in FIG. 6) and a transmission request packet for requesting data transmission are transmitted based on the comparison result by the comparison means. Selection means for selecting the first mode to be transmitted or the second mode in which the transmission request packet is not transmitted (for example, the CPU 3 in FIG. 2 for executing the processing in step S4 or step S6 in FIG. 6) Characterized in that it comprises a) and.

  The wireless communication method according to claim 4 receives a signal (for example, received signal strength indication signal) transmitted from a wireless station (for example, access point 4 in FIG. 1), and sets the received power value of the received signal. A calculation step (for example, step S1 and step S2 in FIG. 6) to be calculated, and a comparison step (for example, step S3 in FIG. 6) for comparing the received power value calculated by the processing of the calculation step with a predetermined threshold value. And a selection step (for example, selecting a first mode in which a transmission request packet for requesting data transmission is transmitted or a second mode in which a transmission request packet is not transmitted is based on a comparison result by the processing in the comparison step. Step S4 or Step S6) of FIG. 6 is included.

  Note that, in the program recorded on the recording medium according to claim 5 and the program according to claim 6, the embodiment (however, an example) corresponding to each step is the information processing according to claim 4. It is the same as the method.

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

  FIG. 1 is a diagram illustrating a configuration example of a wireless communication system in a hidden inter-terminal state according to the present invention.

  Under the control of an access point (radio base station) 4 as a receiving station that constitutes the radio communication system 1, there are a terminal 2 and a terminal 3 as transmitting stations. Since the obstacle 5 exists between the terminal 2 and the terminal 3, they cannot recognize each other and the carrier sense does not operate normally. Further, since the reception power from the terminal 2 is larger than the reception power from the terminal 3, the access point 4 has a capture effect even if the data packet from the terminal 2 collides with the data packet from the terminal 3. Although the data packet from 2 is normally received, the data packet from the terminal 3 cannot be normally received. That is, the data packet from the terminal 3 is canceled and discarded.

  Although only the terminal 2 and the terminal 3 are illustrated in the wireless communication system 1 in FIG. 1, it goes without saying that there are a plurality of terminals under the access point 4.

  FIG. 2 is a block diagram illustrating an internal configuration example of the wireless communication units of the terminal 2 and the terminal 3. As shown in the figure, the wireless communication unit 12 includes an RF (Radio Frequency) unit 21 and a baseband processing unit 22 that processes digital signals. The baseband processing unit 22 includes a demodulation unit 31, a MAC (Media Access Control) processing unit 32, a CPU (Central Processing Unit) 33, a ROM (Read Only Memory) 34, a RAM (Random Access Memory) 35, and a modulation unit 36. It is configured.

  The antenna 11 performs wireless communication with the access point 4. The RF unit 21 amplifies the RF signal received via the antenna 11, performs predetermined high-frequency signal processing such as frequency conversion processing and A / D (Analog to Digital) conversion processing, and supplies the high-frequency signal processing to the demodulation unit 31. To do. The RF unit 21 performs predetermined high-frequency signal processing such as D / A conversion processing and frequency conversion processing on the signal supplied from the modulation unit 36 and transmits the obtained RF signal via the antenna 11. .

  The demodulator 31 demodulates the data supplied from the RF unit 21 and supplies it to the MAC processor 32. The modulation unit 36 modulates the data supplied from the MAC processing unit 32 and supplies it to the RF unit 21.

  The MAC processing unit 32 performs radio signal MAC frame processing on the demodulated data supplied from the demodulating unit 31 and supplies it to the CPU 33. Further, the MAC processing unit 32 performs radio signal MAC frame processing on the transmission data supplied from the CPU 33 and supplies it to the modulation unit 36.

  The CPU 33 expands the control program stored in the ROM 34 in the RAM 35 and controls the MAC processing unit 32. Further, the CPU 33 stores data necessary for executing various processes in the RAM 35. Further, the CPU 33 receives the received power at the access point 4 of its own terminal based on RSSI (Received Signal Strength Indicator) supplied from the RF unit 21 via the demodulator 31 and the MAC processor 32. And the setting of the RTS transmission mode and the RTS non-transmission mode are switched based on the calculation result. These modes are stored in the ROM 34. Note that, for calculating received power, not only RSSI but also a dedicated device for calculating received power may be provided.

  FIG. 3 is a timing chart for explaining data packet transmission processing when RTS / CTS is not used. FIG. 3A represents the sequence of the terminal 2 with high received power, FIG. 3B represents the sequence of the terminal 3 with low received power, and the horizontal axis represents time.

  The terminal 2 transmits data packets 51 to 62 to the access point 4. The terminal 3 transmits the data packet 71 to the access point 4 at the timing when the data packets 51 to 55 are transmitted from the terminal 2, and the data is transmitted to the access point 4 at the timing when the data packets 58 to 62 are transmitted from the terminal 2. Packet 72 is transmitted.

  In this case, although packet collision occurs, the reception power of the terminal 2 at the access point 4 is larger than that of the terminal 3, so that the access point 4 normally receives only the data packets 51 to 62 from the terminal 2. To do. On the other hand, since the data packets 71 and 72 of the terminal 3 having low reception power are canceled and discarded due to packet collision, the access point 4 cannot normally receive these packets.

  FIG. 4 is a timing chart for explaining data packet transmission processing when the terminal 2 uses RTS / CTS. 4A represents the sequence of the terminal 2 with high received power, FIG. 4B represents the sequence of the terminal 3 with low received power, and the horizontal axis represents time.

  The terminal 2 transmits an RTS (transmission request packet) 81 requesting transmission of a data packet to the access point 4 and notifies that the data packet transmitted from the access point 4 can be received. A request response packet (not shown) is received and a data packet 91 is transmitted. Similarly, the terminal 2 transmits RTSs 82 to 84 to the access point 4 at respective timings, receives a CTS (not shown) transmitted from the access point 4, and transmits data packets 92 to 94 to the respective data packets 92 to 94. Send at the timing.

  The terminal 3 transmits the data packet 101 to the access point 4 and transmits the data packets 102 to 105 to the access point 4 at the timing when the RTSs 81 to 84 are transmitted from the terminal 2, respectively.

  In this case, although packet collision occurs, the reception power of the terminal 2 at the access point 4 is larger than that of the terminal 3, so that the access point 4 normally receives only the data packets 91 to 94 from the terminal 2. To do. However, the extra bandwidth is used as much as RTS / CTS is used, resulting in reduced throughput. On the other hand, since the data packets 102 to 105 of the terminal 3 with low reception power are canceled and discarded due to packet collision, the access point 4 cannot normally receive these packets.

  FIG. 5 is a timing chart for explaining data packet transmission processing when the terminal 3 uses RTS / CTS. FIG. 5A represents the sequence of the terminal 2 with high reception power, FIG. 5B represents the sequence of the terminal 3 with low reception power, and the horizontal axis represents time.

  The terminal 2 transmits data packets 111 to 118 to the access point 4.

  The terminal 3 transmits the RTS 121 to the access point 4 at the timing when the data packet 112 is transmitted from the terminal 2. However, since the terminal 2 is transmitting the data packet 112, the CTS from the access point 4 cannot be received, and the RTS 122 is retransmitted after a predetermined time has elapsed. However, since the terminal 2 is transmitting the data packet 114, the CTS from the access point 4 cannot be received, and the RTS 123 is retransmitted after a predetermined time has elapsed. Thereafter, the terminal 3 receives a CTS (not shown) transmitted from the access point 4 and transmits a data packet 131.

  Further, the terminal 3 transmits the RTS 124 to the access point 4 at the timing when the data packet 117 is transmitted from the terminal 2. However, since the terminal 2 is transmitting a data packet, the CTS from the access point 4 cannot be received, and the RTS 125 is retransmitted. Thereafter, the terminal 3 receives a CTS (not shown) transmitted from the access point 4 and transmits a data packet 132.

  In this case, although packet collision occurs, the reception power of the terminal 2 at the access point 4 is larger than that of the terminal 3, so that the access point 4 normally receives only the data packets 111 to 118 from the terminal 2. To do. On the other hand, the RTSs 121 and 122 and the RTS 124 of the terminal 3 with low reception power are canceled and discarded due to packet collision. However, in the case of normal reception such as RTS 123 and RTS 125, the bandwidth can be secured and the data packet 131 and the data packet 132 can be transmitted.

  As can be seen from FIGS. 3 to 5, in the present invention, in the case of a terminal (terminal 2 in the example of FIG. 1) whose received power from the access point 4 is larger than a predetermined threshold, it is shown in FIG. In the case of a terminal that selects a mode that does not use RTS / CTS and the received power from the access point 4 is smaller than a predetermined threshold (terminal 3 in the example of FIG. 1), the RTS / CTS shown in FIG. Switch to select the mode that uses CTS.

  Next, a transmission mode selection process executed by the terminal (in the example of FIG. 1, terminal 2 or terminal 3) will be described with reference to the flowchart of FIG. It is assumed that the reception power of the terminal has not yet been calculated before starting this process.

  In step S <b> 1, the antenna 11 receives data (for example, RSSI: received signal strength indication signal) from the access point 4. Received data is subjected to predetermined high-frequency signal processing by the RF unit 21, demodulated by the demodulation unit 31, and subjected to MAC frame processing by the MAC processing unit 32. In step S <b> 2, the CPU 33 calculates the value of the reception power of the reception data based on the data supplied from the RF unit 21 via the demodulation unit 31 and the MAC processing unit 32.

  In step S3, the CPU 33 determines whether or not the value of the received power calculated in the process of step S2 is greater than a predetermined threshold. If the CPU 33 determines that the value of the received power is greater than the predetermined threshold, the process proceeds to step S4. Go ahead and switch settings to select RTS non-transmission mode.

  In step S <b> 5, the CPU 33 supplies data to be transmitted to the MAC processing unit 32. The transmission data is subjected to MAC frame processing by the MAC processing unit 32, modulated by the modulation unit 36, and subjected to predetermined high-frequency signal processing by the RF unit 21. The antenna 11 transmits the data packet supplied from the CPU 33 via the MAC processing unit 32, the modulation unit 36, and the RF unit 21 to the access point 4.

  As described above, when the received power value of the own terminal is large, it is determined that the received power at the access point 4 of the own terminal is also large. Data packets can be canceled. Therefore, if the CPU 33 determines that the value of the received power is larger than the predetermined threshold value, it is not necessary to consider the overhead of the RTS, and the data is transmitted at a higher speed if only the data packet is transmitted without transmitting the RTS. Can be transmitted.

  In step S3, when it is determined that the value of the reception power calculated in the process of step S2 is not larger than the predetermined threshold value, that is, it is determined to be smaller, the process proceeds to step S6, and the CPU 33 is set to select the RTS transmission mode. Switch. In step S <b> 7, the CPU 33 transmits an RTS (transmission request packet) requesting the access point 4 to transmit a data packet via the MAC processing unit 32, the modulation unit 36, the RF unit 21, and the antenna 11. When the access point 4 normally receives the RTS, the access point 4 transmits a CTS (request response packet) notifying that the data packet can be received to the terminal.

  In step S8, the CPU 33 determines whether or not a CTS has been received from the access point 4. If it is determined that no CTS has been received, the CPU 33 returns to step S7 and repeats the retransmission of the RTS. If it is determined in step S8 that the CTS has been received from the access point 4, the process proceeds to step S9, and the CPU 33 transmits the data packet via the MAC processing unit 32, the modulation unit 36, the RF unit 21, and the antenna 11. Transmit to access point 4.

  As described above, when the received power value of the own terminal is small, it is determined that the received power at the access point 4 of the own terminal is also small. It will be negated and it will be in the state which cannot communicate almost. Therefore, when the CPU 33 determines that the value of the received power is smaller than the predetermined threshold, it secures the bandwidth by transmitting the RTS and continues the communication, so that it is most efficient for the own terminal in the hidden terminal environment. Data can be transmitted.

  The series of processes described above can be executed by hardware or can be executed by software. In this case, for example, the terminal 2 and the terminal 3 include a computer 200 as shown in FIG.

  In FIG. 7, the CPU 201 executes various processes according to a program stored in the ROM 202 or a program loaded from the storage unit 108 to the RAM 203. The RAM 203 also appropriately stores data necessary for the CPU 201 to execute various processes.

  The CPU 201, the ROM 202, and the RAM 203 are connected to each other via the bus 204. An input / output interface 205 is also connected to the bus 204.

  The input / output interface 205 includes an input unit 206 including a keyboard and a mouse, a display including a CRT (Cathode Ray Tube) and an LCD (Liquid Crystal display), an output unit 207 including a speaker, and a hard disk. A communication unit 209 including a storage unit 208 and a modem is connected. The communication unit 209 performs communication processing via a network including the Internet.

  A drive 210 is connected to the input / output interface 205 as necessary, and a removable medium 211 such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory is appropriately mounted, and a computer program read from them is It is installed in the storage unit 208 as necessary.

  When the above-described series of processing is executed by software, a program constituting the software is installed from a network or a recording medium.

  As shown in FIG. 7, the recording medium is distributed to distribute the program to the user separately from the apparatus main body, and includes a magnetic disk (including a floppy disk (registered trademark)) on which the program is recorded. Removable media consisting of optical disks (including CD-ROM (compact disk-read only memory), DVD (digital versatile disk)), magneto-optical disks (including MD (mini-disk) (registered trademark)), or semiconductor memory In addition to the configuration 211, the configuration includes a ROM 202 on which a program is recorded and a hard disk included in the storage unit 208, which is distributed to the user in a state of being incorporated in the apparatus main body in advance.

  In the present specification, the step of describing the program recorded on the recording medium is not limited to the processing performed in chronological order according to the described order, but is not necessarily performed in chronological order. It also includes processes that are executed individually.

  Further, in this specification, the system represents the entire apparatus constituted by a plurality of apparatuses.

It is a figure which shows the structural example of the radio | wireless communications system of the state between hidden terminals which concerns on this invention. It is a block diagram which shows the example of an internal structure of the radio | wireless communication part of the terminal of FIG. 6 is a timing chart for explaining data packet transmission processing when RTS / CTS is not used. 10 is a timing chart for explaining data packet transmission processing when a terminal having high reception power uses RTS / CTS. 10 is a timing chart for explaining data packet transmission processing when a terminal with low received power uses RTS / CTS. It is a flowchart explaining a transmission mode selection process. And FIG. 16 is a block diagram illustrating a configuration example of a personal computer.

Explanation of symbols

  1 wireless communication system, 2, 3 terminal, 4 access point, 5 obstacle, 11 antenna, 12 wireless communication unit, 21 RF unit, 22 baseband processing unit, 31 demodulation unit, 32 MAC processing unit, 33 CPU, 34 ROM , 35 RAM, 3 modulators, 210 drives, 211 removable media

Claims (7)

In a wireless communication system comprising a wireless station and a terminal wirelessly communicating with the wireless station,
The radio station is
A transmission means for transmitting a signal;
The terminal
Calculating means for receiving the signal transmitted from the wireless station and calculating a received power value of the received signal;
Comparing means for comparing the received power value calculated by the calculating means with a predetermined threshold;
Selection means for selecting a first mode in which a transmission request packet for requesting data transmission is transmitted or a second mode in which the transmission request packet is not transmitted based on a comparison result by the comparison means. A wireless communication system. The selection unit selects the second mode when it is determined that the received power value is larger than the threshold value as a result of the comparison by the comparing unit, and is determined that the received power value is smaller than the threshold value. The wireless communication system according to claim 1, wherein the first mode is selected. Calculating means for receiving a signal transmitted from a radio station and calculating a received power value of the received signal;
Comparing means for comparing the received power value calculated by the calculating means with a predetermined threshold;
Selection means for selecting a first mode in which a transmission request packet for requesting data transmission is transmitted or a second mode in which the transmission request packet is not transmitted based on a comparison result by the comparison means. A wireless communication device. The selection unit selects the second mode when it is determined that the received power value is larger than the threshold value as a result of the comparison by the comparing unit, and is determined that the received power value is smaller than the threshold value. In the case, the wireless communication apparatus according to claim 3, wherein the first mode is selected. A calculation step of receiving a signal transmitted from a wireless station and calculating a received power value of the received signal;
A comparison step of comparing the received power value calculated by the calculation step with a predetermined threshold;
A selection step of selecting a first mode in which a transmission request packet for requesting data transmission is transmitted or a second mode in which the transmission request packet is not transmitted based on a comparison result obtained by the comparison step. A wireless communication method. A calculation step of receiving a signal transmitted from a wireless station and calculating a received power value of the received signal;
A comparison step of comparing the received power value calculated by the calculation step with a predetermined threshold;
A selection step of selecting a first mode in which a transmission request packet for requesting data transmission is transmitted or a second mode in which the transmission request packet is not transmitted based on a comparison result obtained by the comparison step. A recording medium on which a computer-readable program is recorded. A calculation step of receiving a signal transmitted from a wireless station and calculating a received power value of the received signal;
A comparison step of comparing the received power value calculated by the calculation step with a predetermined threshold;
A selection step of selecting a first mode in which a transmission request packet for requesting data transmission is transmitted or a second mode in which the transmission request packet is not transmitted based on a comparison result obtained by the comparison step; A program characterized by being executed.

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