阅读说明：本技术 无线通信设备、无线通信终端和无线通信方法 (Wireless communication device, wireless communication terminal, and wireless communication method ) 是由 平田龙一 森冈裕一 相尾浩介 于 2018-12-28 设计创作，主要内容包括：本技术涉及允许避免全双工通信中的分组冲突的无线通信设备、无线通信终端和无线通信方法。无线通信系统包括充当基站的无线通信设备和作为从单元与该无线通信设备进行通信的一个或多个无线通信终端。该无线通信设备的控制单元设置适当性信息,指示在从无线通信设备发送分组的下行链路发送时段期间是否可以接收从无线通信终端发送的分组,并且无线通信设备的通信单元发送包括该适当性信息的分组。在从无线通信设备发送分组的下行链路发送时段期间,每个无线通信终端的控制单元根据分组中包括的适当性信息来控制分组向无线通信设备的发送,该适当性信息指示是否可以接收从无线通信终端发送的分组。本技术可应用于例如支持全双工通信的无线通信设备。(The present technology relates to a wireless communication device, a wireless communication terminal, and a wireless communication method that allow avoiding packet collisions in full-duplex communication. A wireless communication system includes a wireless communication device serving as a base station and one or more wireless communication terminals communicating with the wireless communication device as slave units. The control unit of the wireless communication device sets appropriateness information indicating whether or not a packet transmitted from the wireless communication terminal can be received during a downlink transmission period in which the packet is transmitted from the wireless communication device, and the communication unit of the wireless communication device transmits the packet including the appropriateness information. During a downlink transmission period in which a packet is transmitted from the wireless communication device, the control unit of each wireless communication terminal controls transmission of the packet to the wireless communication device according to appropriateness information included in the packet, the appropriateness information indicating whether or not the packet transmitted from the wireless communication terminal can be received. The present technology is applicable to, for example, a wireless communication device supporting full duplex communication.)

1. A wireless communication device in a wireless communication system including the wireless communication device acting as a base station and one or more wireless communication terminals communicating with the wireless communication device as slaves, the wireless communication device comprising:

a controller configured to set appropriateness information indicating whether or not a packet transmitted from the wireless communication terminal can be received during a downlink transmission period in which the wireless communication device transmits a packet; and

a communication section configured to transmit a packet including the suitability information.

2. The wireless communication device of claim 1, wherein

The controller sets the suitability information to indicate whether reception is possible or not, in accordance with a state of uplink communication in which a packet is transmitted from the wireless communication terminal to the wireless communication device.

3. The wireless communication device of claim 2, wherein

The controller sets the propriety information to indicate whether reception is possible or not, according to a state of uplink communication during a downlink transmission period.

4. The wireless communication device of claim 1, wherein

The packet from the wireless communication device includes a header portion and a data portion, and

the appropriateness information is included in a header portion or a data portion in a packet from the wireless communication device.

5. The wireless communication device of claim 1, wherein

The packet from the wireless communication device includes a header portion and a data portion, and

the appropriateness information is included in a header portion and a data portion of a packet from the wireless communication device.

6. The wireless communication device of claim 1, wherein

A part of a signal or a subcarrier in a part of a communication band when a packet from the wireless communication device is transmitted to the wireless communication terminal is used as the appropriateness information.

7. The wireless communication device of claim 1, wherein

The appropriateness information is included at a plurality of locations of packets from the wireless communication device.

8. A wireless communication method in a wireless communication system including the wireless communication apparatus serving as a base station and one or more wireless communication terminals communicating with the wireless communication apparatus as slaves, the wireless communication method comprising:

setting appropriateness information indicating whether or not a packet transmitted from the wireless communication terminal can be received during a downlink transmission period in which the wireless communication device transmits a packet; and

transmitting a packet including the appropriateness information.

9. A wireless communication terminal in a wireless communication system including a wireless communication device serving as a base station and one or more wireless communication terminals communicating with the wireless communication device as slaves, the wireless communication terminal comprising:

a controller that controls transmission of a packet to the wireless communication device according to appropriateness information included in the packet during a downlink transmission period in which the wireless communication device transmits the packet, the appropriateness information indicating whether or not the packet transmitted from the wireless communication terminal can be received.

10. The wireless communication terminal of claim 9, wherein

The packet from the wireless communication device also includes an address, and

a controller controls transmission of packets to the wireless communication device according to the address and the appropriateness information.

11. The wireless communication terminal of claim 10, wherein

The controller starts preparation for transmitting a packet to the wireless communication device in a case where no interference occurs with a wireless communication terminal corresponding to the address and the suitability information indicates receptivity.

12. The wireless communication terminal of claim 11, wherein

The appropriateness information is included at a plurality of locations in a packet from the wireless communication device, and

in a case where the suitability information indicating that reception is impossible is detected from a packet being received from the wireless communication device after the controller starts preparation for transmission of the packet to the wireless communication device and before the controller starts transmission of the packet to the wireless communication device, the controller suspends transmission of the packet to the wireless communication device.

13. A wireless communication method in a wireless communication system including a wireless communication apparatus serving as a base station and one or more wireless communication terminals communicating with the wireless communication apparatus as slaves, the wireless communication method comprising:

during a downlink transmission period in which the wireless communication device transmits a packet, transmission of the packet to the wireless communication device is controlled in accordance with appropriateness information included in the packet, the appropriateness information indicating whether or not the packet transmitted from the wireless communication terminal can be received.

Technical Field

The present technology relates to a wireless communication device, a wireless communication terminal, and a wireless communication method, and particularly relates to a wireless communication device, a wireless communication terminal, and a wireless communication method that allow avoiding collisions between packets in full-duplex communication.

Background

At present, as a technique for achieving higher efficiency of wireless communication, full duplex communication in which transmission and reception can be simultaneously performed has been studied. A wireless communication device and a wireless communication terminal corresponding to full duplex communication can simultaneously transmit and receive packets. Therefore, a significant improvement in frequency utilization efficiency can be expected.

For example, in order to efficiently utilize the simultaneous transmission and reception function of an extension wireless station, patent document 1 discloses a technique that allows an extension wireless station that performs transmission or reception to communicate with another extension wireless station.

Reference list

Patent document

Patent document 1: japanese patent laid-open publication No. 2017-028341

Disclosure of Invention

Technical problem

In a full duplex communication system configured with a wireless communication apparatus and a wireless communication terminal that support full duplex communication, the wireless communication apparatus and the wireless communication terminal can perform simultaneous transmission and reception. Therefore, for example, it is considered that uplink communication from a first wireless communication terminal serving as a first slave unit to a wireless communication device serving as a base station (master unit) and downlink communication from the base station to a second wireless communication terminal serving as a second slave unit are simultaneously performed.

However, depending on the deployment of the base station, the first slave unit and the second slave unit, for example, uplink communication from the first slave unit to the base station interferes with downlink communication from the base station to the second slave unit. This may result in a collision between a packet transmitted by the base station and a packet transmitted by the first slave unit, whereby the second slave unit may not be able to receive a packet transmitted from the base station to the second slave unit in downlink communication.

In addition, in the case where the base station performs downlink communication to the second slave unit and receives a packet from the first slave unit, when the third wireless communication terminal serving as the third slave unit starts uplink communication to the base station, collision between the packet transmitted by the first slave unit and the packet transmitted by the third slave unit may occur, whereby the base station may not be able to receive the packet.

The present technology is conceived in view of such a situation, and enables collision between packets in full duplex communication to be avoided.

Solution to the problem

A wireless communication apparatus of the present technology is a wireless communication apparatus in a wireless communication system including the wireless communication apparatus serving as a base station and one or more wireless communication terminals communicating with the wireless communication apparatus as slave units, the wireless communication apparatus comprising: a controller configured to set propriety (propriety) information indicating whether or not a packet transmitted from the wireless communication terminal can be received during a downlink transmission period in which the wireless communication device transmits the packet; and a communication section configured to transmit a packet including the suitability information.

A first wireless communication method of the present technology is a wireless communication method in a wireless communication system including the wireless communication apparatus serving as a base station and one or more wireless communication terminals communicating with the wireless communication apparatus as slave units, the wireless communication method comprising: setting appropriateness information indicating whether or not a packet transmitted from the wireless communication terminal can be received during a downlink transmission period in which the wireless communication device transmits a packet; and transmitting a packet including the appropriateness information.

In a wireless communication device and a first wireless communication method of the present technology, in a wireless communication system including a wireless communication device serving as a base station and one or more wireless communication terminals communicating with the wireless communication device as slave units, appropriateness information indicating whether or not a packet transmitted from the wireless communication terminal can be received during a downlink transmission period when the wireless communication device transmits the packet is set, and a packet including the appropriateness information is transmitted.

A wireless communication terminal of the present technology is a wireless communication terminal in a wireless communication system including a wireless communication apparatus serving as a base station and one or more wireless communication terminals communicating with the wireless communication apparatus as a slave unit, the wireless communication system including the wireless communication apparatus serving as the base station and the one or more wireless communication terminals communicating with the wireless communication apparatus as the slave unit, the wireless communication terminal comprising: a controller that controls transmission of a packet to the wireless communication device according to appropriateness information included in the packet during a downlink transmission period in which the wireless communication device transmits the packet, the appropriateness information indicating whether or not the packet transmitted from the wireless communication terminal can be received.

A second wireless communication method of the present technology is a wireless communication method in a wireless communication system including a wireless communication apparatus serving as a base station and one or more wireless communication terminals communicating with the wireless communication apparatus as slave units, the wireless communication method comprising: during a downlink transmission period in which the wireless communication device transmits a packet, transmission of the packet to the wireless communication device is controlled in accordance with appropriateness information included in the packet, the appropriateness information indicating whether or not the packet transmitted from the wireless communication terminal can be received.

In the wireless communication device and the second wireless communication method of the present technology, in a wireless communication system including a wireless communication device serving as a base station and one or more wireless communication terminals communicating with the wireless communication device as slave units, during a downlink transmission period when the wireless communication device transmits a packet, transmission of the packet to the wireless communication device is controlled in accordance with appropriateness information included in the packet, the appropriateness information indicating whether or not the packet transmitted from the wireless communication terminal can be received.

Advantageous effects of the invention

According to the present technology, collisions between packets can be avoided in full duplex communication.

Note that the effect described herein is not necessarily limited, and may be any effect described in the present disclosure.

Drawings

Fig. 1 is a view showing a configuration example of an embodiment of a wireless communication system to which the present technology is applied.

Fig. 2 is a block diagram showing a configuration example of the communication device 20.

Fig. 3 is a block diagram showing a configuration example of the communication device 30.

[ FIG. 4 ]]Fig. 4 is a diagram showing a state from the AP1 (communication device 20) to the STA # i (communication device 30)_i) Is shown in a first embodiment of the format of a packet transmitted in downlink communications.

Fig. 5 is a sequence diagram illustrating an example of operations performed in AP1 and STA1 to STA 4.

Fig. 6 is a flowchart illustrating an example of processing executed in the AP 1.

Fig. 7 is a flowchart illustrating an example of processing performed in STA # i.

[ FIG. 8 ]]Fig. 8 is a diagram showing transmission from the AP1 (communication device 20) to the STA # i (communication device 30) in downlink communication_i) A view of a second embodiment of the format of the DL packet of (1).

Fig. 9 is a flowchart illustrating an example of processing performed in the AP1 in the case where the DL packet in fig. 8 is transmitted.

Fig. 10 is a flowchart illustrating an example of processing performed in the STA # i in the case where the DL packet in fig. 8 is transmitted.

Fig. 11 is a block diagram showing a configuration example of an embodiment of a computer to which the present technology is applied.

Detailed Description

< Wireless communication System >

Fig. 1 is a view showing a configuration example of an embodiment of a wireless communication system to which the present technology is applied.

The wireless communication system 10 shown in fig. 1 constitutes, for example, a wireless LAN (local area network) standardized in IEEE (institute of electrical and electronics engineers) 802.11, and includes a communication apparatus 20, a communication apparatus 30₁Communication device 30₂Communication device 30₃And a communication device 30₄。

The communication device 20 is a wireless communication device serving as a base station (master unit) in the wireless LAN, and is a wireless communication device supporting full duplex communication that can simultaneously perform transmission and reception.

Communication device 30₁To 30₄Is a wireless communication terminal, such as a smartphone, acting as a slave unit in a wireless LAN.

Communication device 20 and communication device 30_iWireless communication conforming to the standard of IEEE 802.11, for example, is performed.

The communication device 20 is also described herein as an AP (access point) 1. Communication device 30₁Communication device 30₂Communication device 30₃And a communication device 30₄Also described as STA (station) 1, STA2, STA3, and STA4, respectively. A communication in which a packet is transmitted from the AP1 to STA # i (here, i ═ 1, 2, 3, and 4) is also described as a downlink communication. In contrast, communication in which a packet is transmitted from the STA # i to the AP1 is also described as uplink communication.

In fig. 1, a communication device 30₁(STA1) is performing uplink communication (UL: uplink) to the communication device 20(AP1), and the communication device 20(AP1) is performing uplink communication to the communication device 30₂Downlink communication (DL: downlink) of (STA 2).

Hereinafter, the communication device 30 is not required to be used₁To 30₄In the case of distinguishing from each other, only the communication device 30 is optionally used₁To 30₄Referred to as the communication device 30.

Note that the configuration of the wireless communication system 10 shown in fig. 1 is an example, and is not limited to this example. In addition, for example, the number of the communication devices 20 or the communication devices 30 is arbitrary and is not limited to the embodiment in fig. 1.

< communication apparatus >

Fig. 2 is a block diagram showing a configuration example of the communication device 20.

As shown in FIG. 2, the communication device 20 includes a data processor 51, a controller 52, a communication section 53, an antenna 66₁To 66_NAnd a power supply section 71. The communication section 53 includes a modulation/demodulation section 61, a signal processor 62, a channel estimation section 63, and a radio interface 64₁To 64_NAnd an amplifier 65₁To 65_N。

In the case where the data processor 51 transmits data input from the protocol upper layer, that is, a packet (frame) is transmitted, the data processor 51 generates a packet for performing wireless transmission from the data input from the protocol upper layer. In addition, the data processor 51 performs data processing such as addition of a header and an error detection code to perform media access control (MAC (media access control)). The data processor 51 supplies the packet obtained by the data processing to the modulation/demodulation section 61.

In the case where the data processor 51 receives data from the modulation/demodulation section 61 (i.e., a packet is received), the data processor 51 performs data processing such as analysis of a MAC header, detection of a packet error, and reordering processing on the packet supplied from the modulation/demodulation section 61. The data processor 51 supplies data obtained by this data processing to the protocol upper layer.

The controller 52 is provided with various sections (a data processor 51, a controller 52, and a communication section 53 (a modulation/demodulation section 61, a signal processor 62, a channel estimation section 63, a radio interface 64)₁To 64_NAnd an amplifier 65₁To 65_N) Inter-conveyingAnd (4) information. In addition, the controller 52 performs control of the respective sections, such as parameter setting in the modulation/demodulation section 61 and the signal processor 62, scheduling of packets in the data processor 51, and the radio interface 64₁To 64_NAnd amplifier 65₁To 65_NAnd control of the transmit power.

In the case of performing downlink communication, the controller 52 determines whether or not a packet of the communication device 30 in uplink communication can be received according to the state of the communication device 30 in uplink communication, and sets propriety information indicating whether or not a packet transmitted from the communication device 30 can be received during a downlink transmission period in which the communication device 20 transmits the packet, according to the determination result. Further, the controller 52 controls the respective sections to include the appropriateness information in the packet in the downlink communication.

The communication section 53 performs processing necessary for transmitting and receiving packets by wireless communication, and passes through the antenna 66_iTransmission and reception of packets are performed.

Antenna 66_iThe packet supplied from the communication section 53 is transmitted as a wireless signal. In addition, an antenna 66_iThe wireless signal of the packet is received and supplied to the communication section 53.

In the case where the packet is transmitted, the modulation/demodulation section 61 performs transform processing such as encoding, interleaving, and modulation on the packet supplied from the data processor 51 based on the encoding method and the modulation method whose parameters are set by the controller 52, and generates a data symbol stream. The modulation/demodulation section 61 supplies the generated data symbol stream to the signal processor 62.

On the other hand, in the case where a packet is received, the modulation/demodulation section 61 performs a process reverse (inverse) to the process in the case where the packet is transmitted described above on the data symbol stream supplied from the signal processor 62. In other words, the modulation/demodulation section 61 performs inverse processing such as demodulation, deinterleaving, and decoding on the data symbol stream supplied from the signal processor 62, and supplies a packet obtained by the inverse processing to the data processor 51 and the controller 52.

In the case where a packet is transmitted, the signal processor 62 performs signal processing including spatial processing such as MIMO (multiple input and multiple output) on the data symbol stream supplied from the modulation/demodulation section 61 as necessary, and generates one or more transmission symbol streams. The signal processor 62 supplies each generated transmit symbol stream to the radio interface 64_i。

On the other hand, in the case where a packet is received, the signal processor 62 pairs the slave wireless interface 64_iThe supplied received symbol stream performs signal processing, performs spatial processing on the received symbol stream as necessary, and supplies the resultant data symbol stream to the modulation/demodulation section 61.

The channel estimation section 63 is based on the slave radio interface 64_iThe preamble portion and the training signal portion of the supplied received symbol stream are used to calculate the complex channel gain of the propagation path. The channel estimation section 63 supplies the calculated complex channel gain to the modulation/demodulation section 61 and the signal processor 62 through the controller 52. The modulation/demodulation section 61 performs demodulation processing using the complex channel gain supplied from the channel estimation section 63. The signal processor 62 uses the complex channel gain supplied from the channel estimation section 63 for spatial processing.

In the case where a packet is transmitted, the wireless interface 64_iThe transmission symbol stream DA (digital to analog) input from the signal processor 62 is converted into an analog signal, and processing such as filtering and up-conversion to a carrier frequency is performed. Wireless interface 64_iThe transmission signal obtained through the processing such as DA conversion, filtering, and up-conversion to the carrier frequency is supplied to the amplifier 65_i。

On the other hand, in the case where a packet is received, the wireless interface 64_iFor the signal from amplifier 65_iPerforms a process reverse to the process in the case where the packet is transmitted, and supplies a signal (reception symbol stream) obtained by the reverse process to the signal processor 62 and the channel estimation section 63.

In the case where a packet is transmitted, the amplifier 65_iWill come from the wireless interface 64_iAmplifies to a predetermined power, and the communication device 20From an antenna 66_iThe amplified transmission signal is transmitted as a radio signal (signal is radiated in the air).

In the case where a packet is received, the amplifier 65_iWill be transmitted by the antenna 66_iThe received wireless signal is amplified to a predetermined power and supplied as a received signal to the wireless interface 64_i。

Note that amplifier 65 is concerned_iAt least one of the functions at the time of transmission or the functions at the time of reception may be included in the wireless interface 64_iIn (1). Both the function at the time of transmission and the function at the time of reception are included in the wireless interface 64_iIn the case of (1), without amplifier 65_iThe communication unit 53 is constituted in the case of (1).

The power supply section 71 is constituted by a battery power supply or a fixed power supply, and supplies power to each section in the communication device 20.

Wireless interface 64_iAmplifier 65_iAnd an antenna 66_iThe number of each of them may be arbitrary, and may be one, or may be three or more.

Alternatively, the wireless interface 64_iAmplifier 65_iAnd an antenna 66_iMay be configured as a component (these portions may be configured as a processor).

Fig. 3 is a block diagram showing a configuration example of each communication device 30.

As shown in fig. 3, each communication device 30 includes a data processor 151, a controller 152, a communication section 153, an antenna 166₁To 166_NAnd a power supply section 171. The communication section 153 includes a modulation/demodulation section 161, a signal processor 162, a channel estimation section 163, and a radio interface 164₁To 164_NAnd an amplifier 165₁To 165_N。

Herein, the data processor 51 and the communication section 53 (modulation/demodulation section 61, signal processor 62, channel estimation section 63, wireless interface 64) shown in fig. 2 are respectively connected to₁To 64_NAnd an amplifier 65₁To 65_N) Antenna 66₁To 66_NData processing is configured similarly to the power supply section 71Processor 151 and communication unit 153 (modulation/demodulation unit 161, signal processor 162, channel estimation unit 163, and radio interface 164)₁To 164_NAnd an amplifier 165₁To 165_N) Antenna 166₁To 166_NAnd a power supply section 171, and thus description is omitted.

Similar to the controller 52 in fig. 2, the controller 152 is configured by various sections (the data processor 151 and the communication section 153 (the modulation/demodulation section 161, the signal processor 162, the channel estimation section 163, the radio interface 164)₁To 164_NAnd an amplifier 165₁To 165_N) To communicate information therebetween. In addition, similar to the controller 52 in fig. 2, the controller 152 performs control of various parts such as parameter setting in the modulation/demodulation section 161 and the signal processor 162, scheduling of packets in the data processor 151, and the radio interface 164₁To 164_NAnd amplifier 165₁To 165_NAnd control of the transmit power.

In addition, the controller 152 determines whether or not a packet can be transmitted to the communication device 20 based on the appropriateness information included in the packet in the downlink communication (i.e., the packet from the communication device 20), and controls transmission of the packet to the communication device 20 according to the result of the determined appropriateness. In other words, in the case where the suitability information indicates receptibility in which a packet can be received, the controller 152 starts preparation for transmission of the packet, and transmits the packet. In the case where the suitability information indicates non-reception that indicates that the packet cannot be received, the controller 152 controls the respective parts to suspend (refrain) transmission of the packet.

< DL grouping >

Fig. 4 is a diagram showing a transmission from the AP1 (communication device 20) to the STA # i (communication device 30) in downlink communication_i) Is shown in the first embodiment of the format of the packet.

Herein, a packet transmitted from the AP1 to the STA # i in downlink communication is also referred to as a DL packet. The DL packet of the first embodiment includes one piece of propriety information in the header portion.

The DL packet shown in fig. 4 is, for example, a packet standardized in IEEE 802.11ax, and is configured while arranging a PHY (physical) Header (PHY Header) as a Header portion of the DL packet and data (MAC) as a data portion of the DL packet in turn. In the header portion, L-STF, L-LTF, L-SIG, RL-SIG, HE-SIG-A, HE-STF, and HE-LTF are arranged in order.

In the AP1, for example, propriety information indicating the propriety of the AP1 receiving the packet may be included in a header portion in the DL packet. Regarding the appropriateness information, a new field is extended in the HE-SIG-a in the header portion, and the appropriateness information may be included in the new field thus extended. Alternatively, the appropriateness information may be included in a portion defined as reserved in the HE-SIG-a in the header portion.

Note that the propriety information may be included in any position other than the HE-SIG-a in the header portion. Alternatively, a field as a new header portion is extended between the header portion and the data portion, and the appropriateness information may be included in the new field.

Otherwise, the appropriateness information may be included in a field of the DL packet for including other existing information. In addition, the appropriateness information may be included in any position such as the middle, head, or tail of the HE-SIG-a.

Fig. 5 is a sequence diagram illustrating an example of operations performed in the AP1 and STAs 1 to 4.

The AP1 and the STA # i include information on the possibility of performing an operation according to the propriety information at, for example, the start of connection in, for example, a "capability field" in each packet to be exchanged at, for example, the start of connection, and transmit and receive each packet. With this configuration, the AP1 and the STA # i mutually determine (grasp) whether or not an operation according to the propriety information can be performed. In addition, the STA # i performs transmission and reception (exchange) of packets with another STA # i, and stores reception power of a signal transmitted from the other STA # i.

In fig. 5, the horizontal axis represents time. In addition, in fig. 5, a solid line indicates a transmission operation of a packet, and a broken line indicates other operations.

In fig. 5, the AP1 performs downlink communication that transmits DL packets (TxDL) destined for STA 2.

DL packets to be transmitted from AP1 to STA2 in downlink communications include appropriateness information and information about STA2 as an address. A packet addressed to STA2 is received by STA2(RxDL) and is received by STA1, STA3 and STA4 in addition to STA 2.

Herein, in the uplink communication from the STA # i to the AP1, the packet transmitted by the STA # i is also referred to as an UL packet.

Now, for example, assume that the amount of interference to STA2 in the case where STA1 and STA3 each transmit an UL packet in uplink communication is smaller than a first threshold, and the amount of interference to STA2 in the case where STA4 transmits an UL packet to AP1 in uplink communication is larger than the first threshold. Herein, the first threshold is, for example, a fixed value held by the STA # i or a threshold notified from the AP 1.

In STA # i, the amount of interference due to transmission of an UL packet is estimated from the received power stored at the start of connection.

Each of STA1, STA3, and STA4 receives a DL packet addressed to STA2 from AP1, and detects that the address of the DL packet from AP1 is STA2 from the addresses included in the DL packet.

With regard to STA4, in the case where STA4 transmits an UL packet to AP1, the amount of interference to STA2, which is the address of AP1 in downlink communication, is greater than the first threshold, so STA4 suspends transmission of the UL packet to AP1 (busy).

On the other hand, with respect to STA1 and STA3, in the case where each of STA1 and STA3 transmits an UL packet to AP1, the amount of interference to STA2 which is the address of AP1 in downlink communication is smaller than the first threshold, and therefore, in the case where the appropriateness information included in the DL packet addressed to STA2 indicates that reception is possible (the UL packet can be received), STA1 and STA3 start preparation for transmitting the UL packet to AP1, that is, for example, acquisition of transmission right. In the present embodiment, in order to acquire the transmission right, for example, slots (times) having random numbers are set, and back-off is performed that suspends transmission of UL packets for periods corresponding to these slots.

In fig. 5, the waiting time of the STA1 is shown during a period corresponding to one slot, and the waiting time of the STA3 is shown during a period corresponding to two slots. Therefore, STA1 terminates the backoff before STA3 and acquires the transmission right before STA 3. After acquiring the transmission right, the STA1 starts transmitting an UL packet (TxUL) to the AP 1.

At the point in time when STA3 terminates the backoff, STA3 attempts to start transmitting UL packets to AP1, but detects that STA1 is transmitting UL packets to AP1, i.e., detects that a signal with (received) power exceeding (greater than) the second threshold is being transmitted. Based on this detection, STA3 buffers sending UL packets (busy) to avoid collision with the UL packets of STA 1. This may avoid collisions between the UL packets transmitted by STA1 and the UL packets transmitted by STA 3. Herein, the second threshold is, for example, a threshold different from the first threshold, and is, for example, a fixed value held by the STA # i or a threshold notified from the AP 1.

Fig. 6 is a flowchart illustrating an example of processing performed in the AP 1.

In step S11, the AP1 determines whether reception of the UL packet in the uplink communication is possible based on whether the UL packet from the STA # i in the uplink communication is being received (the state of the uplink communication).

In step S11, in the case where the AP1 determines that reception of an UL packet in uplink communication is possible, i.e., in the case where no UL packet is being received from any STA # i, the process proceeds to step S12.

In step S12, the AP1 sets appropriateness information to indicate that reception is possible, and the process advances to step S13.

On the other hand, in step S11, in the case where the AP1 determines that reception of the UL packet in uplink communication is not possible, that is, in the case where the UL packet is being received from any STA # i, the process proceeds to step S15.

In step S15, the AP1 sets appropriateness information to indicate that reception is not possible, and the process advances to step S13.

In step S13, the AP1 starts transmitting a DL packet including the appropriateness information in the header portion, and the process advances to step S14.

In step S14, the AP1 transmits the DL packet until the end of the data part, and then terminates the transmission of the DL packet to terminate the process.

Fig. 7 is a flowchart illustrating an example of processing performed in the STA # i.

In step S21, the STA # i waits for transmission of a DL packet from the AP1, and then starts receiving the DL packet. Then, the process advances from step S21 to step S22.

In step S22, STA # i detects the address of the DL packet from AP1, and STA # i determines whether the amount of interference to the address of the DL packet in the case where STA # i transmits the UL packet to AP1 in uplink communication is less than a first threshold, such as a fixed value held by STA # i or a threshold notified from AP 1.

In step S22, in a case where STA # i determines that the amount of interference to the address of the DL packet in the case where STA # i transmits the UL packet to AP1 in the uplink communication is larger than the first threshold, the process proceeds to step S28.

In step S28, the STA # i suspends transmitting the UL packet to the AP1, and the process terminates.

On the other hand, in step S22, when STA # i determines that the amount of interference with the address of the DL packet is less than the first threshold when STA # i transmits the UL packet to AP1 in uplink communication, the process proceeds to step S23.

In step S23, STA # i determines whether uplink communication (i.e., transmission of an UL packet to AP1) is possible according to the appropriateness information included in the header portion of the DL packet from AP 1.

In step S23, in the case where STA # i determines that uplink communication is not possible, i.e., in the case where the propriety information included in the header portion of the DL packet from AP1 indicates that reception is not possible, the process proceeds to step S28, and STA # i suspends transmission of the UL packet to AP1 as described above.

On the other hand, in step S23, in the case where STA # i determines that uplink communication is possible, i.e., in the case where the propriety information included in the header portion of the DL packet from AP1 indicates that reception is possible, the process proceeds to step S24.

In step S24, as preparation for transmitting the UL packet to the AP1, the STA # i starts acquiring the transmission right and sets a random waiting time (slot by random number). Then, the process advances to step S25.

As described above, in the case where interference does not occur between STA # i and the address to which AP1 is transmitting the DL packet (the amount of interference is smaller than the first threshold), and the suitability information in the DL packet received from AP1 indicates that reception is possible, STA # i starts to prepare to transmit the UL packet to AP 1.

In step S25, the STA # i waits for the termination of backoff (termination of slot), and the process advances to step S26.

In step S26, the STA # i determines whether or not to perform transmission of a signal having (received) power exceeding a second threshold value that is different from the first threshold value and is a fixed value held by the STA # i or a threshold value notified from the AP 1.

In step S26, in a case where STA # i determines that transmission of a signal having power exceeding the second threshold is being performed, the process proceeds to step S28, and STA # i suspends transmission of UL packets to AP1 as described above.

On the other hand, in step S26, if the STA # i determines that the transmission of the signal having the power exceeding the second threshold is not being performed, the process proceeds to step S27.

In step S27, the STA # i starts transmitting UL packets to the AP1, and after the transmission of the last UL packet up to the data part is terminated, the process is terminated.

As described above, while the AP1 transmits the DL packet including the appropriateness information, the STA # i determines whether uplink communication (i.e., transmission of the UL packet to the AP1) is possible, and controls transmission of the UL packet. Accordingly, in the wireless communication system 10, the occurrence of interference between STAs in full duplex communication can be reduced.

Specifically, for example, simultaneous occurrence of multiple uplink communications to the AP1 may be prevented. In addition, the AP1 can be prevented from failing to receive the UL packet in uplink communication, i.e., collisions between packets that occur due to transmission of packets from multiple STAs can be avoided. Further, the AP1 may perform full duplex communication without collecting information such as traffic of STA # i.

Fig. 8 is a diagram showing transmission from the AP1 (communication device 20) to the STA # i (communication device 30) in downlink communication_i) A view of a second embodiment of the format of the DL packet of (1).

The DL packet of the second embodiment includes a plurality of pieces of propriety information.

In fig. 8, the horizontal axis represents time, and the vertical axis represents frequency.

In addition, similar to fig. 3, the DL packet shown in fig. 8 is, for example, a packet standardized in IEEE 802.11ax and is constituted by arranging a PHY Header (PHY Header) as a Header portion in the DL packet and data (MAC) as a data portion in the DL packet in this order.

The appropriateness information may be included in a header portion in the packet, or may be included in the packet in various forms. In addition, the appropriateness information may be included in one location (one location in time or frequency) in the packet, or may be included in a plurality of locations.

Note that the insertion positions are assumed to be predetermined, and are a plurality of positions each including the appropriateness information.

For example, one or more pieces of appropriateness information may be included in a header portion or a data portion in a packet. In addition, one or more pieces of appropriateness information may be included in each of the header portion and the data portion in the packet.

For the suitability information, a signal in a part of a communication band at the time of transmitting a DL packet or a part of subcarriers at the time of transmitting a DL packet may be used. For example, in the case where a part of a signal or subcarrier in a part of a communication band is used for the propriety information, the presence and absence of the signal or subcarrier indicates, for example, that reception is possible and reception is not possible.

In the case where the appropriateness information is included in the header portion and the data portion in the DL packet, the appropriateness information may be included in any field in the header portion, and a signal or subcarrier corresponding to the data portion in the DL packet in the communication band may be used for the appropriateness information, for example.

As described above, the method for including the appropriateness information may be changed between the header part and the data part in the DL packet.

In addition, as described above, by including the appropriateness information at a plurality of positions in the DL packet, even in the case where the state of uplink communication changes during the downlink transmission period of the DL packet and the state of the reception possibility of the UL packet changes, the AP1 includes the appropriateness information indicating the reception possibility of the UL packet after the change in the DL packet during the downlink transmission period, and thus can notify the STA # i of the latest information on the reception possibility of the UL packet.

As a result, the STA # i can determine the reception possibility of the UL packet at the current point in time even in the middle of receiving the DL packet transmitted from the AP1, and can control the transmission of the UL packet to the AP1 based on the determination result.

Herein, for example, in a case where STA # i is receiving a data portion in a DL packet (the DL packet includes appropriateness information only at one position in a header portion) during downlink transmission of the DL packet transmitted by the AP1, for example, when the AP1 receives the UL packet, the AP1 cannot notify STA # i of the fact that reception of the UL packet is impossible.

In other words, when reception of the UL packet is possible, the AP1 starts transmitting the DL packet including the propriety information indicating that reception is possible in the header portion. In the case where a piece of suitability information is included in the header portion of the DL packet transmitted by the AP1, the STA # i receives the DL packet up to the suitability information in the header portion and decides that uplink communication to the AP1 is possible because the suitability information indicates that reception is possible. STA # i then starts transmitting UL packets.

On the other hand, in the case where the AP1 becomes unable to receive the UL packet after the start of transmission of the DL packet, for example, in the case where the AP1 becomes unable to receive the UL packet after the transmission of the header portion in the DL packet, the AP1 cannot notify the STA # i of the fact that the reception of the UL packet is impossible by the appropriateness information included in the header portion in the DL packet until the next DL packet is transmitted.

Thus, as shown in fig. 8, the AP1 may include appropriateness information at multiple locations in the DL packet. For example, by including the appropriateness information at one or more positions in the header portion in the DL packet and one or more positions in the data portion in the DL packet, even in the case where the AP1 becomes unable to receive the UL packet after transmitting the header portion in the DL packet, the AP1 can notify the STA # i of the fact that the AP1 cannot receive the UL packet through the appropriateness information included in the data portion in the DL packet.

For example, as explained in fig. 5, in the case where STA1 and STA3 are about to start transmitting UL packets, when AP1 sets the appropriateness information in the header portion to be receivable and starts transmitting DL packets including the header portion, STA1 and STA3 start acquiring transmission rights as preparation for transmitting UL packets at the point of time when the header portion included in the DL packet from AP1 is received and the appropriateness information that can be received is indicated.

As explained in fig. 5, STA1 acquires the transmission right before STA 3. In the case where the STA1 starts transmitting the UL packet after the transmission of the header portion in the DL packet by the AP1 is terminated and before the data portion is transmitted, the AP1 sets the appropriateness information in the data portion to be transmitted next to be unreceivable in response to the transmission of the UL packet from the STA1 (state of uplink communication), and then the AP1 transmits the data portion.

The STA3 receiving such appropriateness information in the data portion buffers transmitting UL packets to the AP 1. As a result, a collision between the UL packet of STA1 and the UL packet of STA3 due to STA3 starting to transmit the UL packet to AP1 can be avoided.

Note that STA1 starts transmitting UL packets to AP1, and thus STA1 does not receive the data portion including the propriety information indicating that it cannot receive in the DL packet from AP 1. Therefore, the STA1 performs (continues) transmission of the UL packet to the AP 1.

Further, in fig. 5, since STA3 is receiving DL packets from AP1 destined for STA2, STA3 may fail to detect the fact that STA1 starts transmitting UL packets to AP 1. In the event STA3 fails to detect the fact that STA1 is transmitting UL packets to AP1, STA3 begins transmitting UL packets to AP 1. When STA3 starts transmitting UL packets to AP1, a collision occurs between the UL packets of STA1 and the UL packets of STA 3.

Further, when the received power at STA3 of the signal of the UL packet being transmitted from STA1 to AP1 does not exceed the second threshold, STA3 fails to detect the fact that STA1 is transmitting the UL packet to AP 1. This causes STA3 to start transmitting UL packets to AP1, whereby a collision occurs between the UL packets of STA1 and STA 3.

Therefore, when receiving the UL packet from STA1, AP1 sets the appropriateness information included in the data portion in the DL packet being transmitted to be unreceivable, for example, in response to receiving the UL packet (state of uplink communication) from STA 1. In the case where the appropriateness information included in the data portion in the DL packet being received from the AP1 indicates that reception is impossible, the STA3 suspends transmitting the UL packet. This avoids collisions between the UL packets of STA1 and the UL packets of STA3 that occur when STA3 starts transmitting DL packets to AP1 in the event STA3 fails to detect the fact that STA1 starts transmitting UL packets to AP 1.

Fig. 9 is a flowchart illustrating an example of processing performed in the AP1 in the case where the DL packet in fig. 8 is transmitted.

In step S31, the AP1 determines whether reception of the UL packet in the uplink communication is possible based on whether the UL packet in the uplink communication is being received from the STA # i.

In step S31, in the case where the AP1 determines that reception of an UL packet in uplink communication is possible (i.e., no UL packet is being received from any STA # i), the process proceeds to step S32.

In step S32, the AP1 sets appropriateness information to indicate that reception is possible, and the process advances to step S33.

On the other hand, in step S31, in the case where the AP1 determines that reception of the UL packet in uplink communication is impossible (i.e., the AP1 is receiving the UL packet from any STA # i), the process proceeds to step S37.

In step S37, the AP1 sets appropriateness information to indicate that reception is not possible, and the process advances to step S33.

In step S33, the AP1 starts transmitting a DL packet including the propriety information, and the process advances to step S34. When a DL packet is transmitted, the appropriateness information set in step S32 or step S37 is included at the latest insertion position of the DL packet.

In step S34, the AP1 determines whether the AP1 has received an UL packet from STA # i.

In step S34, in the case where the AP1 determines that the AP1 has received an UL packet from the STA # i, that is, in the case where the AP1 has received an UL packet from any STA # i while transmitting the DL packet started in step S32, the process proceeds to step S35.

In step S35, the AP1 sets (changes) the suitability information to indicate that reception is not possible, and the process advances to step S36.

On the other hand, in step S34, in a case where the AP1 determines that the AP1 has not received an UL packet from the STA # i, that is, in a case where the AP1 has not received an UL packet from any STA # i while transmitting the DL packet started in step S32, the process proceeds to step S38.

In step S38, the AP1 sets appropriateness information to indicate that reception is possible, and the process advances to step S36.

Herein, the appropriateness information set in step S35 or step S38 is included at the latest insertion position in the DL packet whose transmission is started in step S33.

In step S36, the AP1 transmits the DL packet until the end of the data part, and then terminates the transmission of the DL packet to terminate the process.

As described above, like the DL packet illustrated in fig. 8, the propriety information is included at a plurality of positions in the DL packet. Therefore, even when the state of uplink communication changes during transmission of a DL packet, the AP1 can notify the STA # i of the possibility of reception of an UL packet in response to the state of uplink communication after the change.

Fig. 10 is a flowchart illustrating an example of processing performed in the STA # i in the case where the DL packet in fig. 8 is transmitted.

In fig. 10, the processes in step S41 to step S45 are performed similarly to the processes in step S21 to step S25 in fig. 7, respectively.

In the case where it is determined in step S42 that the amount of interference to the address of the DL packet in the case of transmitting the UL packet is larger than the first threshold (which is, for example, a fixed value held by the STA # i or a threshold notified from the AP1), and in the case where it is determined in step S43 that it is impossible to transmit the UL packet to the AP1 in uplink communication, the process proceeds to step S48.

In step S48, similar to step S27 in fig. 7, the STA # i suspends transmission of the UL packet to the AP1, and the process terminates.

After terminating the backoff in step S45, in step S46, the STA # i starts receiving the DL packet of step S41 and determines whether or not it is possible to transmit an UL packet to the AP1 in uplink communication, according to the latest appropriateness information currently also included in the received DL packet.

In step S46, in the event that the STA # i determines that an UL packet can be transmitted to the AP1 in uplink communication (i.e., the latest appropriateness information included in the DL packet from the AP1 indicates that reception is possible), the process proceeds to step S47.

In step S47, the STA # i starts transmitting the UL packet to the AP1, and after the last data part in the UL packet is transmitted, the process is terminated.

On the other hand, in step S46, in the event that the STA # i determines that it is not possible to transmit an UL packet to the AP1 in uplink communication (i.e., the latest appropriateness information included in the DL packet from the AP1 indicates that it is not possible to receive), the process proceeds to step S48, and as described above, the STA # i suspends transmission of the UL packet to the AP 1.

In this way, the AP1 transmits DL packets including appropriateness information at a plurality of locations, and the STA # i determines whether or not an UL packet can be transmitted to the AP1 in uplink communication according to the latest appropriateness information included in the DL packets, and controls transmission of the UL packet to the AP 1.

Therefore, in the wireless communication system 10, in the case where the AP1 has been receiving an UL packet from any STA # i, the AP1 transmits a DL packet including propriety information indicating that reception is impossible, thereby preventing multiple uplink communications to the AP1 from occurring at the same time. This may prevent the AP1 from failing to receive the UL packet in the uplink communication, i.e., avoid collisions between packets that occur due to the transmission of packets from multiple STAs.

In addition, as described above, the STA # i receives the DL packet including the propriety information at a plurality of locations from the AP 1. Therefore, in a case where STA # i detects the propriety information indicating that it cannot receive after STA # i starts preparing to transmit the UL packet to AP1 and before STA # i starts transmitting the UL packet to AP1, STA # i decides that the UL packet cannot be transmitted to AP1 in uplink communication and suspends the transmission of the UL packet to AP 1.

Therefore, it is possible to avoid collision between packets that occurs in a case where a plurality of STAs each decide that it is possible to transmit an UL packet to the AP1 in uplink communication and perform transmission of the UL packet to the AP 1.

In other words, for example, it is assumed that the AP1 starts transmitting a DL packet including adequacy information at a plurality of positions (in each of a header portion and a data portion in the DL packet), and the header portion in the DL packet includes adequacy information indicating that it is possible to receive. The STA # i decides that the UL packet can be transmitted to the AP1 in uplink communication by receiving a header portion including suitability information indicating that reception is possible in the DL packet. The STA # i starts preparation for transmission of the UL packet to the AP1 in the uplink communication according to the determination, and starts transmission of the UL packet to the AP1 in the uplink communication. In the AP1, when the AP1 receives an UL packet that starts being transmitted by STA # i, it becomes impossible to receive the UL packet from another STA # j, the appropriateness information included in the data portion of the DL packet being transmitted is set to be unable to be received, and the data portion including such appropriateness information is transmitted.

Similarly to the STA # i, another STA # j other than the STA # i also receives a header portion including the propriety information indicating that it is capable of receiving, and thus starts to prepare to transmit the UL packet to the AP1 in uplink communication. However, when receiving the data part including the propriety information indicating that reception is impossible from the AP1 before starting transmission, the STA # j suspends transmission of the UL packet to the AP1 in uplink communication in response to the propriety information.

As described above, the AP1 transmits DL packets including appropriateness information at a plurality of locations. With this procedure, it is possible to prevent STA # j from immediately starting transmission of the UL packet to AP1 in the uplink communication after STA # i starts transmission of the UL packet to AP1 in the uplink communication, and thus collision between the packets of STA # i and STA # j can be avoided.

Note that in the above description, the case where the present technology is applied to a wireless LAN compliant with IEEE 802.11 is explained. However, the present technology can be applied to wireless full-duplex communication in addition to the wireless LAN compliant with IEEE 802.11.

< computer to which the present technology is applied >

Subsequently, the above-described series of processes of the data processor 51 and the signal processor 62, for example, may be performed by hardware or software. In the case where the series of processes is executed by software, a program constituting the software is installed in a computer.

Thus, fig. 11 shows a configuration example of an embodiment of a computer in which a program that executes the series of processes described above is installed.

In fig. 11, a CPU (central processing unit) 201 executes various processes in accordance with a program stored in a ROM (read only memory) 202 or a program loaded from a storage device 108 into a RAM (random access memory) 203. In the RAM 203, for example, data necessary when the CPU 201 executes various processes is also appropriately stored.

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

The input/output interface 205 is connected with an input section 206 including, for example, a keyboard and a mouse, an output section 207 including, for example, a display such as an LCD (liquid crystal display) and a speaker, a storage device 208 provided with, for example, a hard disk, and a communication section 209 provided with, for example, a modem and a terminal adapter. The communication section 209 performs communication processing through a network such as the internet.

The input/output interface 205 is also connected with a driver 210 as necessary. A removable medium 211 such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory is optionally mounted on the drive 210, and a computer program read from this removable medium 211 is installed in the storage device 208 as necessary.

Note that the program to be executed by the computer may be a program in which processing is performed chronologically in the order described in this specification, or may be a program in which processing is performed in parallel or is performed at a desired timing (for example, when a call is issued).

In addition, the embodiments of the present technology are not limited to the above-described embodiments, and various modifications may be made without departing from the gist of the present technology.

Note that the effects described in this specification are merely illustrative, and not restrictive. Effects other than those described in the present specification can be obtained.

< others >

The present technology can adopt the following configuration.

(1) A wireless communication device in a wireless communication system including the wireless communication device acting as a base station and one or more wireless communication terminals communicating with the wireless communication device as slaves, the wireless communication device comprising:

a controller configured to set appropriateness information indicating whether or not a packet transmitted from the wireless communication terminal can be received during a downlink transmission period in which the wireless communication device transmits a packet; and

a communication section configured to transmit a packet including the suitability information.

(2) The wireless communication device according to (1), wherein

The controller sets the suitability information to indicate whether reception is possible or not, in accordance with a state of uplink communication in which a packet is transmitted from the wireless communication terminal to the wireless communication device.

(3) The wireless communication device according to (1) or (2), wherein

The controller sets the propriety information to indicate whether reception is possible or not, according to a state of uplink communication during a downlink transmission period.

(4) The wireless communication device according to any one of (1) to (3), wherein

The packet from the wireless communication device includes a header portion and a data portion, and

the appropriateness information is included in a header portion or a data portion in a packet from the wireless communication device.

(5) The wireless communication device according to any one of (1) to (3), wherein

The packet from the wireless communication device includes a header portion and a data portion, and

the appropriateness information is included in a header portion and a data portion of a packet from the wireless communication device.

(6) The wireless communication device according to any one of (1) to (5), wherein

A part of a signal or a subcarrier in a part of a communication band when a packet from the wireless communication device is transmitted to the wireless communication terminal is used as the appropriateness information.

(7) The wireless communication device according to any one of (1) to (6), wherein

The appropriateness information is included at a plurality of locations of packets from the wireless communication device.

(8) A wireless communication method in a wireless communication system including the wireless communication apparatus serving as a base station and one or more wireless communication terminals communicating with the wireless communication apparatus as slaves, the wireless communication method comprising:

setting appropriateness information indicating whether or not a packet transmitted from the wireless communication terminal can be received during a downlink transmission period in which the wireless communication device transmits a packet; and

transmitting a packet including the appropriateness information.

(9) A wireless communication terminal in a wireless communication system including a wireless communication device serving as a base station and one or more wireless communication terminals communicating with the wireless communication device as slaves, the wireless communication terminal comprising:

a controller that controls transmission of a packet to the wireless communication device according to appropriateness information included in the packet during a downlink transmission period in which the wireless communication device transmits the packet, the appropriateness information indicating whether or not the packet transmitted from the wireless communication terminal can be received.

(10) The wireless communication terminal according to (9), wherein

The packet from the wireless communication device also includes an address, and

a controller controls transmission of packets to the wireless communication device according to the address and the appropriateness information.

(11) The wireless communication terminal according to (9) or (10), wherein

The controller starts preparation for transmitting a packet to the wireless communication device in a case where no interference occurs with a wireless communication terminal corresponding to the address and the suitability information indicates receptivity.

(12) The wireless communication terminal according to any one of (9) to (11), wherein

The appropriateness information is included at a plurality of locations in a packet from the wireless communication device,

in a case where the suitability information indicating that reception is impossible is detected from a packet being received from the wireless communication device after the controller starts preparation for transmission of the packet to the wireless communication device and before the controller starts transmission of the packet to the wireless communication device, the controller suspends transmission of the packet to the wireless communication device.

(13) A wireless communication method in a wireless communication system including a wireless communication apparatus serving as a base station and one or more wireless communication terminals communicating with the wireless communication apparatus as slaves, the wireless communication method comprising:

during a downlink transmission period in which the wireless communication device transmits a packet, transmission of the packet to the wireless communication device is controlled in accordance with appropriateness information included in the packet, the appropriateness information indicating whether or not the packet transmitted from the wireless communication terminal can be received.

List of labels

10: wireless communication system, 20, 30: communication device, 51: data processor, 52: controller, 53: communication unit, 61: modulation/demodulation section, 62: signal processor, 63: channel estimation section, 64_i: wireless interface, 65_i: amplifier, 66_i: antenna, 71: power supply unit, 151: data processor, 152: controller, 153: communication unit, 161: modulation/demodulation unit, 162: signal processor, 163: channel estimation section, 164_i: wireless interface, 165_i: amplifier, 166_i: antenna, 171: power supply unit, 201: CPU, 202: ROM, 203: RAM, 204: bus, 205: input/output interface, 206: input section, 207: output unit, 208: storage device, 209: communication unit, 210: driver, 211: removable magnetic disk