Wireless communication system and wireless communication device

Abstract

This disclosure relates to a wireless communication system and a wireless communication device. The wireless communication system is provided with a packet decoding unit, a cause estimation unit, and an MCS control unit. The packet decoding unit is configured to execute processing for acquiring a decoding result at the time when a received packet is decoded. The cause estimation unit is configured to execute processing for estimating a transmission failure cause on the basis of the decoding result. The MCS control unit is configured to execute processing for lowering an MCS when the transmission failure cause is noise and processing for increasing the MCS when the transmission failure cause is interference.

Description

Wireless communication system and wireless communication device

[0001] The present disclosure relates to wireless communication systems and devices.

[0002] The IEEE 802.11 standard, which is a wireless LAN communication standard, allows the modulation level and coding rate in primary modulation to be changed. The combination of the modulation level and coding rate is defined as an MCS (Modulation and Coding Scheme).

[0003] In a wireless communication system in which a transmitting terminal and a receiving terminal communicate wirelessly, if a packet transmission from the transmitting terminal fails, the MCS to be applied to the next and subsequent transmissions may be changed. For example, Patent Document 1 discloses a wireless communication system that improves communication quality by appropriately changing the MCS.

[0004] Patent No. 6441486

[0005] To improve communication quality, it is considered necessary to appropriately change the MCS depending on the cause of the transmission failure. However, the above-mentioned wireless communication system does not take into consideration that the transmitting terminal changes the MCS depending on the cause of the transmission failure. Therefore, there is a problem in that the transmitting terminal cannot set an appropriate MCS depending on the cause of the transmission failure.

[0006] In order to solve the above-mentioned problems, a first object of the present disclosure is to provide a wireless communication system in which a transmitting terminal can set an appropriate MCS depending on the cause of a transmission failure.

[0007] A second object of the present disclosure is to provide a wireless communication device that enables a transmitting terminal to set an appropriate MCS depending on the cause of a transmission failure.

[0008] A first aspect of the present disclosure is preferably a wireless communication system including a packet decoding unit, a cause estimation unit, and an MCS control unit, wherein the packet decoding unit is configured to perform a process of obtaining a decoding result when decoding a received packet, the cause estimation unit is configured to perform a process of estimating a cause of transmission failure based on the decoding result, and the MCS control unit is configured to perform a process of lowering the MCS when the cause of the transmission failure is noise, and a process of increasing the MCS when the cause of the transmission failure is interference.

[0009] A second aspect of the present disclosure is a wireless communication device that includes a packet decoding unit and a cause estimation unit, and that notifies an MCS control unit of a cause of transmission failure, wherein the packet decoding unit is configured to perform a process of acquiring a decoding result when decoding a received packet, the cause estimation unit is configured to perform a process of estimating the cause of transmission failure based on the decoding result, and the MCS control unit is preferably configured to perform a process of lowering the MCS when the cause of the transmission failure is noise, and a process of increasing the MCS when the cause of the transmission failure is interference.

[0010] According to the first and second aspects of the present disclosure, the transmitting terminal can set an appropriate MCS depending on the cause of the transmission failure.

[0011] FIG. 1 is a diagram illustrating a configuration example of a wireless communication system according to a first embodiment of the present disclosure. FIG. 2 is a block diagram illustrating a configuration example of a receiving terminal according to the first embodiment of the present disclosure. FIG. 3 is a diagram illustrating a hardware configuration example of a receiving terminal according to the first embodiment of the present disclosure. FIG. 4 is a block diagram illustrating a configuration example of a transmitting terminal according to the first embodiment of the present disclosure. FIG. 5 is a flowchart illustrating an MCS control method according to the first embodiment of the present disclosure. FIG. 6 is a block diagram illustrating a configuration example of a receiving terminal according to a modified example of the first embodiment of the present disclosure. FIG. 7 is a diagram illustrating a configuration example of a wireless communication system according to a second embodiment of the present disclosure. FIG. 8 is a block diagram illustrating a configuration example of a receiving terminal according to the second embodiment of the present disclosure. FIG. 9 is a block diagram illustrating a configuration example of a monitoring terminal according to the first embodiment of the present disclosure. FIG. 10 is a diagram illustrating a configuration example of a wireless communication system according to a third embodiment of the present disclosure. FIG. 11 is a block diagram illustrating a configuration example of a transmitting terminal according to the third embodiment of the present disclosure.

[0012] 1 is a diagram illustrating a configuration example of a wireless communication system according to a first embodiment of the present disclosure. The wireless communication system 100 includes a transmitting terminal 2. The transmitting terminal 2 is a wireless communication device that first transmits data in the wireless communication system 100. The transmitting terminal 2 is, for example, a station (STA).

[0013] The transmitting terminal 2 transmits data to the receiving terminal 4. The receiving terminal 4 is a wireless communication device that receives the data transmitted by the transmitting terminal 2. The receiving terminal 4 is, for example, an AP (Access Point).

[0014] The transmitting terminal 2 and the receiving terminal 4 are wireless communication devices that perform both data transmission and reception during wireless communication.

[0015] The causes of transmission failure and effective countermeasures for them will be described below. In the wireless communication system 100, possible causes of transmission failure can be classified into two types.

[0016] The first cause is noise. Noise is irregular signal fluctuations caused by internal factors of the wireless device or by external factors. For example, noise 14 can be generated by heat generated inside the transmitting terminal 2.

[0017] The second cause is interference. Interference occurs when the wavelength of a signal used by another system overlaps with the signal used by one system, causing interference. For example, an interference device 10 installed near the transmitting terminal 2 and the receiving terminal 4 may cause interference 12 in the wireless communication between the transmitting terminal 2 and the receiving terminal 4.

[0018] The interfering device 10 is a wireless communication device, such as an AP or a STA. The interference 12 also includes interference that cannot be controlled by a Request to Send (RTS) / Clear to Send (CTS) mechanism. Interference that cannot be controlled by the RTS / CTS mechanism is, for example, interference originating from wireless communication using another communication method in the same frequency band.

[0019] When the influence of noise is greater, it is considered effective to lower the MCS, for example, by lowering the modulation level and the coding rate, thereby reducing the error rate.

[0020] On the other hand, if the impact of interference is greater, it is considered effective to increase the MCS. Increasing the MCS means, for example, increasing the modulation level and the coding rate. This shortens the packet length, thereby reducing the probability of packet collisions.

[0021] As described above, the MCS control policy adopted by the transmitting terminal 2 differs depending on the cause of the transmission failure. If the transmitting terminal 2 does not receive an ACK (Acknowledgement) frame response from the receiving terminal 4 within a certain period of time, it can determine that the transmission has failed. However, because the transmitting terminal 2 does not have a mechanism for acquiring the cause of the transmission failure, it has had the problem of being unable to set an appropriate MCS according to the cause of the transmission failure. The present disclosure solves this problem.

[0022] 2 is a block diagram showing an example configuration of a receiving terminal according to the first embodiment of the present disclosure. The receiving terminal 4 includes a transceiver 42. The transceiver 42 transmits data received as packets to a packet decoder 44. The packet decoder 44 decodes the received packets and transmits the decoded information to an upper layer.

[0023] If the receiving terminal 4 fails to properly receive a packet transmitted from the transmitting terminal 2, it notifies the transmitting terminal 2 of the cause of the transmission failure. To this end, the packet decoding unit 44 first transmits the decoding result, which is information acquired when decoding the received packet, to the environment analysis unit 45 and the cause estimation unit 46.

[0024] The environment analysis unit 45 analyzes the decoding result, obtains statistical information as the analysis result, and transmits the analysis result to the cause estimation unit 46.

[0025] The cause estimation unit 46 estimates the cause of the transmission failure based on the received analysis result and decoding result. Specifically, it estimates the ratio of interference to noise in the cause of the decoding failure. Then, it transmits the estimation result to the transceiver unit 42. The transceiver unit 42 notifies the transmitting terminal 2 of the received estimation result.

[0026] When the estimated cause of the transmission failure is interference, the transmitter / receiver 42 may notify wireless communication devices other than the transmitting terminal 2 by broadcasting the estimation result. Alternatively, wireless communication devices other than the transmitting terminal 2 may intercept the estimation result, thereby acquiring the estimated cause of the transmission failure in the wireless communication system 100. This provides wireless communication devices other than the transmitting terminal 2 with an opportunity to perform MCS control, thereby reducing the probability of interference in the entire network.

[0027] 3 is a diagram illustrating an example of a hardware configuration of a receiving terminal according to the first embodiment of the present disclosure. Fig. 3 illustrates a configuration in which the functions of the receiving terminal 4 according to the first embodiment of the present disclosure are realized by software.

[0028] The receiving terminal 4 includes a processor 47 and a memory 48 instead of the packet decoding unit 44, the environment analysis unit 45, and the cause estimation unit 46 in Fig. 2. The memory 48 stores a wireless communication program executed by the processor 47. The receiving terminal 4 can realize functions specific to this embodiment by the processor 47 executing the wireless communication program.

[0029] That is, the functions of the receiving terminal 4 can be realized by a computer and the program. The program can also be recorded on a recording medium or provided via a network.

[0030] 4 is a block diagram showing an example configuration of a transmitting terminal according to the first embodiment of the present disclosure. The transmitting terminal 2 includes a transmitting / receiving unit 22. The transmitting / receiving unit 22 transmits data received as packets to a packet decoding unit 24. The received data includes the estimation result notified from the receiving terminal 4.

[0031] The packet decoder 24 decodes the received packet and transmits it to the MCS controller 28. The MCS controller determines an MCS control method based on the decoded estimation result, and transmits control information for instructing the determined control method to the signal generator 29.

[0032] The signal generator 29 converts the information to be transmitted, received from the upper layer, into a signal using an MCS based on the control information received from the MCS controller. The signal generator 29 then transmits the converted information to the transmitter / receiver 22. The transmitter / receiver 22 transmits the received information to the receiving terminal 4.

[0033] 5 is a flowchart showing the control process of MCS according to the first embodiment of the present disclosure. First, in step 100, the cause of the transmission failure is estimated. In this embodiment, the cause estimation unit 46 of the receiving terminal 4 estimates the cause of the transmission failure based on the received analysis result and decoding result.

[0034] The analysis result is statistical information analyzed based on the successfully decoded packets by the environment analysis unit 45. Examples of the statistical information include the number of other terminals and the airtime occupied by the other terminals.

[0035] The decoding result is information obtained when the packet decoding unit 44 decodes a received packet. Examples of the decoding result include a received signal strength indicator (RSSI) and a packet error occurrence pattern.

[0036] The estimated cause of the transmission failure is noise or interference. More specifically, the cause estimation unit 46 estimates the occurrence rate of packet errors due to noise and packet errors due to interference. This allows the determination of whether the influence of noise or interference is greater.

[0037] Next, in step 102, the MCS control unit 28 checks whether noise is the major cause of the transmission failure. If it is noise, the process proceeds to step 104. If it is not noise, i.e., if it is interference, the process proceeds to step 106.

[0038] In step 104, the MCS is lowered and the process ends. More specifically, based on the estimation result notified from the receiving terminal 4, the MCS control unit 28 determines to lower the MCS.

[0039] In step 106, the MCS is increased and the process ends. More specifically, based on the estimation result notified from the receiving terminal 4, the MCS control unit 28 determines to increase the MCS.

[0040] Through the above process, the transmitting terminal 2 can set an appropriate MCS according to the cause of the transmission failure.

[0041] 6 is a block diagram showing an example configuration of a receiving terminal according to a modification of the first embodiment of the present disclosure. A receiving terminal 4a according to this modification differs from the receiving terminal 4 in that the receiving terminal 4 estimates the cause of a transmission failure based on the waveform of a received packet.

[0042] The receiving terminal 4a includes a transmitting / receiving unit 42. The transmitting / receiving unit 42 transmits data received as packets to a packet decoding unit 44. The packet decoding unit 44 decodes the received packets and transmits the decoded information to an upper layer.

[0043] If the receiving terminal 4 fails to receive a packet transmitted from the transmitting terminal 2 successfully, the receiving terminal 4 notifies the transmitting terminal 2 of the cause of the transmission failure. To this end, the packet decoding unit 44 first transmits the decoding result, which is information acquired when decoding the received packet, to the cause estimation unit 46.

[0044] The cause estimation unit 46 estimates the cause of the transmission failure based on the received decoding result. Specifically, it estimates the ratio of interference to noise in the causes of the decoding failure. The decoding result in this modification includes the bit error pattern of the packet. The cause estimation unit 46 estimates the cause of the transmission failure based on this bit error pattern. For example, it analyzes the preamble portion, which has a fixed bit pattern, and estimates that if inversions occur at random locations, the influence of noise is significant, and if inversions occur in bursts, the influence of interference is significant.

[0045] The cause estimation unit 46 transmits the estimation result to the transmission / reception unit 42. The transmission / reception unit 42 notifies the transmission terminal 2 of the received estimation result.

[0046] According to this modified example, it is possible to estimate the cause of a packet error on a packet-by-packet basis without acquiring statistical information.

[0047] 7 is a diagram illustrating a configuration example of a wireless communication system according to a second embodiment of the present disclosure. A wireless communication system 200 according to this embodiment differs from the wireless communication system 100 in that a receiving terminal 4b is provided instead of the receiving terminal 4, and a monitoring terminal 6 is newly provided.

[0048] The wireless communication system 200 includes a transmitting terminal 2. The transmitting terminal 2 transmits data to a receiving terminal 4b. The receiving terminal 4b differs from the receiving terminal 4 in that it does not include an environment analysis unit 45 or a cause estimation unit 46, as will be described later.

[0049] The wireless communication system 200 also includes a monitoring terminal 6. The monitoring terminal 6 is installed near the transmitting terminal 2 and the receiving terminal 4b, and performs processing to estimate the cause of transmission failure by intercepting wireless communication between the transmitting terminal 2 and the receiving terminal 4b. By installing the monitoring terminal 6 near the transmitting terminal 2 and the receiving terminal 4b, it becomes possible for the monitoring terminal 6 to be affected by interference 12 and noise 14 in the same way as the transmitting terminal 2.

[0050] The monitoring terminal 6 is a wireless communication device that performs the process of estimating the cause of a transmission failure, which was included in the receiving terminal 4 in embodiment 1. That is, the monitoring terminal 6 performs the estimation of the cause of a transmission failure that is performed in step 100 in the flowchart of FIG.

[0051] 8 is a block diagram illustrating a configuration example of a receiving terminal according to the second embodiment of the present disclosure. The receiving terminal 4b has a configuration different from the receiving terminal 4 in that it does not include the environment analysis unit 45 and the cause estimation unit 46.

[0052] 9 is a block diagram showing an example configuration of a monitoring terminal according to the first embodiment of the present disclosure. The monitoring terminal 6 includes a transceiver 62. The transceiver 62 transmits data received as packets to a packet decoder 64. The packet decoder 64 may decode the received packets and transmit the decoded information to a higher layer.

[0053] If the monitoring terminal 6 fails to receive a packet transmitted from the transmitting terminal 2 successfully, the monitoring terminal 6 notifies the transmitting terminal 2 of the cause of the transmission failure. To this end, the packet decoding unit 64 first transmits the decoding result, which is information acquired when decoding the received packet, to the environment analysis unit 65 and the cause estimation unit 66.

[0054] The environment analysis unit 65 analyzes the decoding result, obtains statistical information as the analysis result, and transmits the analysis result to the cause estimation unit 66.

[0055] The cause estimation unit 66 estimates the cause of the transmission failure based on the received analysis result and decoding result. Specifically, it estimates the ratio of interference to noise in the cause of the decoding failure. Then, it transmits the estimation result to the transceiver unit 62. The transceiver unit 62 notifies the transmitting terminal 2 of the received estimation result.

[0056] If the estimated cause of the transmission failure is interference, the transmitter / receiver 62 may notify wireless communication devices other than the transmitting terminal 2 by broadcasting the estimation result. Alternatively, wireless communication devices other than the transmitting terminal 2 may intercept the estimation result, thereby obtaining the estimated cause of the transmission failure in the wireless communication system 200. This provides wireless communication devices other than the transmitting terminal 2 with an opportunity to perform MCS control, thereby reducing the probability of interference in the entire network.

[0057] By the above processing, even in a wireless communication system using a receiving terminal 4b and a transmitting terminal 2 that do not have a mechanism for estimating the cause of transmission failure, it is possible to notify the transmitting terminal 2 of the cause of transmission failure. This allows the transmitting terminal 2 to set an appropriate MCS according to the cause of transmission failure.

[0058] 10 is a diagram illustrating a configuration example of a wireless communication system according to a third embodiment of the present disclosure. The wireless communication system 300 differs from the wireless communication system 100 in that the wireless communication system 300 includes a receiving terminal 4b instead of the receiving terminal 4 and a transmitting terminal 2a instead of the transmitting terminal 2.

[0059] The wireless communication system 300 includes a transmitting terminal 2a. As will be described later, the transmitting terminal 2a differs from the transmitting terminal 2 in that it has a function for estimating the cause of a transmission failure. The transmitting terminal 2a performs wireless communication with the receiving terminal 4b.

[0060] 11 is a block diagram showing a configuration example of a transmitting terminal according to the third embodiment of the present disclosure. The transmitting terminal 2a includes a transmitting / receiving unit 22. The transmitting / receiving unit 22 transmits data received as packets to a packet decoding unit 24. The received data includes, for example, an ACK frame transmitted from the receiving terminal 4b upon successful transmission.

[0061] The packet decoding unit 24 transmits the decoding result, which is information acquired when decoding the received packet, to the environment analysis unit 25 .

[0062] The environment analysis unit 25 analyzes the decoding result, obtains statistical information as the analysis result, and transmits the analysis result to the cause estimation unit 26.

[0063] The cause estimation unit 26 estimates the cause of the transmission failure based on the received analysis result and decoding result. Specifically, it estimates the ratio of interference to noise in the cause of the decoding failure. Then, it transmits the estimation result to the MCS control unit 28.

[0064] The MCS control unit determines an MCS control method based on the decoded estimation result, and then transmits control information for instructing the determined control method to the signal generation unit 29.

[0065] The signal generator 29 converts the information to be transmitted, received from the upper layer, into a signal using an MCS based on the control information received from the MCS controller. The signal generator 29 then transmits the converted information to the transmitter / receiver 22. The transmitter / receiver 22 transmits the received information to the receiving terminal 4.

[0066] The transmitting terminal 2a is a wireless communication device that performs the process of estimating the cause of a transmission failure, which was included in the receiving terminal 4 in embodiment 1. That is, the transmitting terminal 2a performs the estimation of the cause of a transmission failure that is performed in step 100 in the flowchart of FIG.

[0067] Through the above process, the transmitting terminal 2a can autonomously estimate the cause of the transmission failure without relying on the cause of the transmission failure notified by other terminals. This allows the transmitting terminal 2a to set an appropriate MCS according to the cause of the transmission failure.

[0068] 2, 2a Transmitting terminal 4, 4a, 4b Receiving terminal 6 Monitoring terminal 12 Interference 14 Noise 24 Packet decoding unit 25 Environment analysis unit 26 Cause estimation unit 44 Packet decoding unit 45 Environment analysis unit 46 Cause estimation unit 64 Packet decoding unit 65 Environment analysis unit 66 Cause estimation unit 100, 200, 300 Wireless communication system

Claims

1. A wireless communication system comprising a packet decoding unit, a cause estimation unit, and an MCS control unit, wherein the packet decoding unit is configured to perform a process of obtaining a decoding result when decoding a received packet, the cause estimation unit is configured to perform a process of estimating a cause of a transmission failure based on the decoding result, and the MCS control unit is configured to perform a process of lowering an MCS when the cause of the transmission failure is noise, and a process of increasing an MCS when the cause of the transmission failure is interference.

2. The wireless communication system of claim 1, further comprising an environmental analysis unit, wherein the environmental analysis unit is configured to perform a process of analyzing the decoding results obtained from the packet decoding unit and obtaining statistical information as the analysis result, and the cause estimation unit is configured to perform a process of estimating the cause of the transmission failure based on the analysis result in addition to the decoding result.

3. The wireless communication system according to claim 1, comprising a receiving terminal, a transmitting terminal and a monitoring terminal, any one of the receiving terminal, the transmitting terminal and the monitoring terminal having the cause estimation unit.

4. A wireless communication device comprising a packet decoding unit and a cause estimation unit, and notifying an MCS control unit of a cause of a transmission failure, wherein the packet decoding unit is configured to perform a process of obtaining a decoding result when decoding a received packet, the cause estimation unit is configured to perform a process of estimating the cause of the transmission failure based on the decoding result, and the MCS control unit is configured to perform a process of lowering the MCS when the cause of the transmission failure is noise, and a process of raising the MCS when the cause of the transmission failure is interference.

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