Wireless communication method, wireless communication system, transmission device, and program

Abstract

Disclosed is a wireless communication method using a plurality of wireless channels and at least one backup wireless channel. According to the method disclosed herein, packets to be transmitted are distributed to a plurality of queues corresponding to the plurality of wireless channels. In addition, a portion of the packets transmitted by the plurality of wireless channels are copied to a backup queue, corresponding to the backup wireless channel, in equal proportions from the plurality of wireless channels. Further, in response to a reason for switching occurring in one of the plurality of wireless channels, the transmission of packets from the wireless channel having the reason for switching is switched to the transmission of packets from the backup wireless channel.

Description

Wireless communication method, wireless communication system, transmitting device, and program

[0001] The present disclosure relates to digital wireless communication techniques using multiple wireless channels and at least one spare wireless channel.

[0002] A typical example of the transmission capacity per radio channel in digital radio communications is 155.52 Mbit / s in the STM-1 transmission standard. A typical radio communication system utilizes multiple radio channels and virtually bundles them together to achieve high-capacity data transmission. It has also been proposed to provide a backup radio channel in a radio communication system in case a radio device in one of the radio channels fails or the communication environment deteriorates due to radio interference. For example, Non-Patent Document 1 discloses that in digital radio communications, when a line is disconnected due to a failure of an active device or interference in an active frequency channel, the disconnected frequency channel is automatically switched to a redundant frequency channel (backup radio channel).

[0003] However, in the conventional technology disclosed in Non-Patent Document 1, packets transmitted during the period when the communication environment is being judged to be degraded and during the period when the channel is being switched to a backup wireless channel are discarded without being retransmitted. Since packet loss reduces communication quality, even in situations where the wireless channel must be switched, it is desirable to reduce the impact of packet discards that accompany the switch as much as possible.

[0004] Takaaki Ichikawa, "Study on Diversity Systems in Digital Wireless Communications," Doctoral Dissertation, 14401-08048, July 31, 2000, Osaka University

[0005] The present disclosure has been made in view of the above-mentioned problems, and aims to reduce the impact of packet discarding when switching wireless channels in digital wireless communication using multiple wireless channels and at least one spare wireless channel.

[0006] The present disclosure provides a method for achieving the above object. The method of the present disclosure is a wireless communication method using multiple wireless channels and at least one spare wireless channel. The method of the present disclosure includes the following first to third steps. The first step is a step of distributing packets to be transmitted to multiple queues corresponding to the multiple wireless channels. The second step is a step of copying some of the packets to be transmitted on the multiple wireless channels to a spare queue corresponding to at least one spare wireless channel in equal proportions among the multiple wireless channels. And the third step is a step of switching from transmission of packets from the wireless channel having the switching reason to transmission of packets from at least one spare wireless channel in response to the occurrence of a switching reason in any of the multiple wireless channels.

[0007] The present disclosure also provides a system for achieving the above object. The system of the present disclosure is a wireless communication system having multiple wireless channels and at least one spare wireless channel. The system of the present disclosure includes at least one processor and at least one memory coupled to or incorporated in the at least one processor. The at least one memory stores multiple instructions executable by the at least one processor. The multiple instructions are configured to cause the at least one processor to perform the following first to third processes. The first process is a process of distributing packets to be transmitted to multiple queues corresponding to the multiple wireless channels. The second process is a process of copying some of the packets transmitted over the multiple wireless channels to a spare queue corresponding to the at least one spare wireless channel in equal proportions among the multiple wireless channels. And the third process is a process of switching from transmission of packets from the wireless channel having the switching reason to transmission of packets from the at least one spare wireless channel in response to the occurrence of a switching reason in one of the multiple wireless channels.

[0008] The present disclosure also provides an apparatus for achieving the above object. The apparatus of the present disclosure is a transmitting apparatus that transmits packets using multiple wireless channels and at least one spare wireless channel. The apparatus of the present disclosure includes at least one processor and at least one memory coupled to or incorporated in the at least one processor. The at least one memory stores multiple instructions executable by the at least one processor. The multiple instructions are configured to cause the at least one processor to perform the following first to third processes. The first process is a process of distributing packets to be transmitted to multiple queues corresponding to the multiple wireless channels. The second process is a process of copying some of the packets transmitted over the multiple wireless channels to a spare queue corresponding to the at least one spare wireless channel in equal proportions among the multiple wireless channels. The third process is a process of switching from transmission of packets from the wireless channel having the switching reason to transmission of packets from the at least one spare wireless channel in response to the occurrence of a switching reason in one of the multiple wireless channels.

[0009] The present disclosure also provides a program for achieving the above object. The program of the present disclosure is a program that causes a transmitting device to transmit packets using multiple wireless channels and at least one spare wireless channel. The program of the present disclosure includes multiple instructions executable by at least one processor of the transmitting device. The multiple instructions are configured to cause the at least one processor to perform the following first to third processes. The first process is a process of distributing packets to be transmitted to multiple queues corresponding to the multiple wireless channels. The second process is a process of copying some of the packets transmitted over the multiple wireless channels to a spare queue corresponding to at least one spare wireless channel at equal rates among the multiple wireless channels. The third process is a process of switching from transmission of packets from the wireless channel having the switching reason to transmission of packets from at least one spare wireless channel in response to a switching reason occurring in one of the multiple wireless channels. Note that the program of the present disclosure may be stored in a computer-readable non-transitory storage medium or provided to the transmitting device via a network.

[0010] According to the technology disclosed herein, some of the packets transmitted over the multiple wireless channels are copied to a backup queue corresponding to the backup wireless channel. Therefore, even if a switching event occurs for one of the multiple wireless channels, some of the packets that were not transmitted over the target wireless channel are transmitted over the backup wireless channel. Furthermore, because packets are copied equally among the multiple wireless channels, packets from all wireless channels are included in a certain proportion of the packets transmitted over the backup wireless channel. Therefore, according to the technology disclosed herein, the impact of packet discarding when switching wireless channels is mitigated regardless of which wireless channel is the target of switching.

[0011] FIG. 1 is a diagram showing the configuration of a wireless communication system to which the wireless communication method of the first embodiment is applied and its operation under normal conditions. FIG. 2 is a diagram showing the configuration of a wireless communication system to which the wireless communication method of the first embodiment is applied and its operation when a switching reason occurs. FIG. 3 is a diagram explaining the details of the wireless communication method of the first embodiment. FIG. 4 is a diagram explaining the effect of the wireless communication method of the first embodiment. FIG. 5 is a diagram showing the configuration of a wireless communication system to which the wireless communication method of the second embodiment is applied and its operation under normal conditions. FIG. 6 is a diagram explaining the effect of the wireless communication method of the second embodiment. FIG. 7 is a diagram showing an example of the configuration of a transmitting device for implementing the wireless communication method of the first embodiment. FIG. 8 is a diagram showing an example of the configuration of a receiving device for implementing the wireless communication method of the first embodiment and the wireless communication method of the second embodiment. FIG. 9 is a diagram showing an example of a hardware configuration common to the wireless communication systems of both the first embodiment and the second embodiment. FIG. 10 is a flow chart showing an example of the flow of system operation common to the wireless communication systems of both the first embodiment and the second embodiment.

[0012] 1. First Embodiment An overview of a wireless communication method according to a first embodiment of the present disclosure and a wireless communication system to which the method is applied will be described with reference to Figures 1 and 2. The wireless communication system 1 of the first embodiment is a system that performs packet communication between a transmitting device 10 and a receiving device 20. The wireless communication system 1 is used, for example, as a relay system that relays user data from a device installed in one location to a device installed in another location.

[0013] FIG. 1 shows the configuration and normal operation of a wireless communication system 1. The wireless communication system 1 includes multiple wireless channels and at least one backup wireless channel. The wireless channels are regular wireless channels, and the backup wireless channel is used temporarily when a switching event occurs. The transmission capacity of a typical wireless channel is 155.52 Mbit / s, or STM-1 (Synchronous Transport Module level-1). Therefore, for example, to transmit 1 Gbit / s user data, seven wireless channels must be bundled together for transmission. In the example shown in FIG. 1, seven wireless channels, A, B, C, D, E, F, and G, are provided. Also, in the example shown in FIG. 1, one backup wireless channel H is provided. In FIG. 1, for example, CA refers to wireless channel A, and CH refers to backup wireless channel H. Note that the wireless communication system 1 uses frequency division duplex as its communication method, and wireless channels A to G and backup wireless channel H are arranged on the frequency axis.

[0014] The transmitting device 10 includes a user interface 12. A packet P of user data input to the user interface 12 is first sent to a global queue 13. The packet P in the global queue 13 is then distributed to seven wireless channels A-G. More specifically, queues 14A-14G are provided for the seven wireless channels A-G, respectively. The packet P in the global queue 13 is distributed to the seven queues 14A-14G. Packets PA-PG, extracted in chronological order from each queue 14A-14G, are transmitted over the corresponding wireless channel A-G. In FIG. 1, for example, PA denotes a packet of packet P distributed to wireless channel A, and PG denotes a packet of packet P distributed to wireless channel 14G.

[0015] In the wireless communication system 1, packets are also transmitted via the spare wireless channel H. The spare wireless channel H is provided with a spare queue 14H. Some of the packets transmitted via the wireless channels A to G are copied to the spare queue 14H. Specifically, packets PA-PG are copied to the spare queue 14H at equal rates across the wireless channels A to G. For example, a round-robin method is used to select packets to be copied to the spare queue 14H. If the transmission capacity of one wireless channel is 155.52 Mbit / s, packets of 22.2 Mbit / s, which is one-seventh of 155.52 Mbit / s, are copied from each of the wireless channels A to G to the spare queue 14H. Therefore, one-seventh of the packets PA-PG transmitted via each of the wireless channels A to G are transmitted via the spare wireless channel H.

[0016] 2 shows the configuration of the wireless communication system 1 and its operation when a switching event occurs. The switching of wireless channels can be caused by a line fault, specifically, a line disconnection due to equipment failure, or quality degradation due to radio interference or fading. Forced interruptions for inspection are also a reason for switching wireless channels.

[0017] 2, some switching event occurs in wireless channel A. In this case, the distribution destination of packet P is switched from queues 14A-14G to queues 14B-14G and spare queue 14H, and packet PA distributed to queue 14A is transferred to spare queue 14H. In this way, the wireless channel is switched from wireless channel A to spare wireless channel H.

[0018] Packets PA that were scheduled to be transmitted on the radio channel A during the period until switching from the radio channel A to the spare radio channel H are discarded on the radio channel A. However, one-seventh of the packets transmitted on the spare radio channel H before the radio channel switching is performed are packets PA copied from the radio channel A. In other words, at least a part of the packets PA that were scheduled to be transmitted on the radio channel A are transmitted on the spare radio channel H. This reduces the impact of discarding packets when switching the radio channel.

[0019] Furthermore, according to the wireless communication method of the first embodiment, when switching from the wireless channel A to the backup wireless channel H, the packets PA accumulated in the queue 14A of the wireless channel A are not discarded but are transferred to the backup queue 14H of the backup wireless channel H. Details of the wireless communication method of the first embodiment will be described below with reference to FIGS.

[0020] The wireless communication method of the first embodiment includes steps A1, B1, and C1. Steps A1, B1, and C1 are executed in order when a switching event is detected in any of the wireless channels.

[0021] In step A1, packets in the backup queue 14H of the backup wireless channel H are discarded except for packets copied from the wireless channel for which the occurrence of a switching event has been detected. In the example shown in Fig. 3, the wireless channel for which the switching event has occurred is wireless channel A. Therefore, packets other than packet PA copied from the queue 14A of wireless channel A are discarded from the backup queue 14H. The process of step A1 is executed at the timing when the occurrence of a switching event has been detected.

[0022] In step B1, all packets in the queue corresponding to the wireless channel having the switching reason are moved to the spare queue 14H. In the example shown in Fig. 3, all packets PA in the queue 14A of wireless channel A are moved to the spare queue 14H. The process of step B1 is executed together with the process of step A1 at the timing when the occurrence of the switching reason is detected.

[0023] Then, in step C1, the distribution destination of the packet that was to be distributed to the wireless channel having the switching reason is switched to the backup wireless channel H. In the example shown in Fig. 3, the packet PA is transferred from the queue 14A to the backup queue 14H, and the distribution destination of the packet PA is switched from the queue 14A to the backup queue 14H. In this way, the wireless channel is switched from the wireless channel A, for which the occurrence of the switching reason has been detected, to the backup wireless channel H.

[0024] 4 is a diagram illustrating the effects of the wireless communication method of the first embodiment compared to a conventional wireless communication method. In both the conventional wireless communication method and the wireless communication method of the first embodiment, the wireless channel in which a switching event occurs is designated as wireless channel A.

[0025] First, the problems associated with the conventional wireless communication method will be described. The upper part of Fig. 4 shows the queue 14A at the time of the occurrence of a failure in the conventional wireless communication method, and the packet transmission history on wireless channel A and backup wireless channel H after the failure occurred. There is a time lag between the occurrence of a failure and its detection. Furthermore, there is a time lag between the detection of a failure and the start of wireless channel switching and the completion of the switching. For this reason, a considerable time lag occurs between the detection of a failure and the completion of the switching, and all packets distributed to queue 14A during that time are discarded.

[0026] In the example shown in Fig. 4, packets up to #2A have been transmitted on wireless channel A when a failure occurs. After switching from wireless channel A to backup wireless channel H is completed, packets #12A and onward are transmitted on backup wireless channel H. As a result, according to the conventional wireless communication method, packets #3A to #11A are discarded. Note that #iA means the ith packet in the time series of wireless channel A. For example, #2A means the second packet among the packets distributed to wireless channel A.

[0027] Next, the effects of the wireless communication method of the first embodiment will be described. The lower part of Fig. 4 shows the queue 14A and the backup queue 14H at the time of occurrence of a failure in the wireless communication method of the first embodiment, and the packet transmission history on wireless channel A and backup wireless channel H after the failure occurred. When a failure occurs, packet transmission on wireless channel A stops, but packet transmission on backup wireless channel H continues. Since packets on wireless channels A to G are copied in a round-robin manner to the backup queue 14H of backup wireless channel H, even after packet transmission on wireless channel A stops, some of the packets that were to be transmitted on wireless channel A are transmitted on backup wireless channel H. Then, when a failure is detected, all packets in the backup queue 14H other than those copied from wireless channel A are discarded, and all packets in the queue 14A are moved to the backup queue 14H.

[0028] 4, when the failure occurs, packets up to #2A are being transmitted on wireless channel A. Even after the failure occurs, the packets (packets of A) that have been copied to the spare queue 14H are transmitted on spare wireless channel H. After the failure is detected, packets from #7A onwards in the queue 14A are moved to the spare queue 14H, and packets from #7A onwards are transmitted on spare wireless channel H. As described above, according to the wireless communication method of the first embodiment, the influence of discarding packets when switching wireless channels can be reduced compared to conventional wireless communication methods.

[0029] In the example shown in FIG. 4, the time lag between the occurrence of a fault and its detection is four packets, but this is merely an example. The time lag between the occurrence of a fault and its detection varies depending on the situation. In this example, the reason for switching is a fault, but if the reason for switching is, for example, a periodic inspection, the time lag between the occurrence of the reason for switching and its detection is shorter. Conversely, there may be cases where it takes longer between the occurrence of the reason for switching and its detection. In any situation, the wireless communication method of the first embodiment can reduce the impact of packet discarding when switching wireless channels.

[0030] 2. Second Embodiment Next, an overview of a wireless communication method according to a second embodiment of the present disclosure and a wireless communication system to which the method is applied will be described with reference to Figures 5 and 6. In Figures 5 and 6, elements common to the wireless communication system 1 of the first embodiment are denoted by common reference numerals. In the following description, overlapping descriptions of content common to the wireless communication method and wireless communication system of the first embodiment will be omitted or simplified.

[0031] Fig. 5 shows the configuration of the wireless communication system 2 and its normal operation. The wireless communication system 2 has multiple wireless channels and at least one spare wireless channel. In the example shown in Fig. 5, seven wireless channels, channel A to channel G, are provided. In addition, in the example shown in Fig. 5, channel H is provided as a spare channel. Each of the wireless channels A to G is provided with a sub-queue 18A to 18G in addition to the queues 14A to 14G. The sub-queues 18A to 18G are queues that are several packets deeper than the queues 14A to 14G.

[0032] Packets P in the overall queue 13 are distributed to seven queues 14A-14G. Packets PA-PG distributed to the queues 14A-14G are copied to the sub-queues 18A-18G corresponding to the queues 14A-14G. Packets PA-PG extracted from the queues 14A-14G and transmitted on radio channels A-G are evenly copied to the spare queue 14H using a round-robin method. Therefore, for example, a packet PA queued in queue 14A is also queued in the sub-queue 18A, and with a one in seven probability is also queued in the spare queue 14H.

[0033] Packets PA-PG retrieved from the queues 14A-14G are transmitted on the radio channels A-G. Packets retrieved from the backup queue 14H are transmitted on the backup radio channel H. Each packet transmitted on the backup radio channel H contains one-seventh of the packets PA-PG. On the other hand, when the radio channels A-G are in normal use, packets in the sub-queues 18A-18G are not transmitted, and the oldest packets are discarded each time a new packet is received.

[0034] 6 shows the configuration of the wireless communication system 2 and its operation when a switching event occurs. In the example shown in FIG. 6, some switching event occurs in wireless channel A. In this case, the distribution destination of packets P is switched from queues 14A-14G to queues 14B-14G and spare queue 14H, and packets PA distributed to queue 14A are transferred to spare queue 14H. During this switching, packets PA that are not transmitted on wireless channel A are discarded. However, one-seventh of the packets PA discarded on wireless channel A are transmitted on spare wireless channel H. This reduces the impact of packet discards when wireless channels are switched.

[0035] Furthermore, according to the wireless communication method of the second embodiment, when switching from wireless channel A to backup wireless channel H, untransmitted packets PA are transferred to the backup queue 14H of the backup wireless channel H. In the first embodiment, packets PA accumulated in the queue 14A are transferred to the backup queue 14H, but in the second embodiment, packets PA accumulated in the sub-queue 18A are transferred to the backup queue 14H. Details of the wireless communication method of the second embodiment will be described below with reference to FIGS. 7 and 8.

[0036] The wireless communication method of the second embodiment includes steps A2, B2, and C2. Steps A2, B2, and C2 are executed in order when a switching event is detected in any of the wireless channels.

[0037] In step A2, packets in the backup queue 14H of the backup wireless channel H other than packets copied from the wireless channel for which the occurrence of a switching event has been detected are discarded. In the example shown in Fig. 7, the wireless channel having the switching event is wireless channel A. Therefore, packets other than packet PA copied from wireless channel A are discarded from the backup queue 14H. The process of step A2 is executed at the timing when the occurrence of a switching event is detected.

[0038] In step B2, all packets in the sub-queue corresponding to the radio channel having the switching reason are moved to the spare queue 14H. In the example shown in Fig. 7, all packets PA in the sub-queue 18A of radio channel A are moved to the spare queue 14H. The process of step B2 is executed together with the process of step A2 at the timing when the occurrence of the switching reason is detected.

[0039] Then, in step C2, the distribution destination of the packet that was to be distributed to the wireless channel having the switching reason is switched to the backup wireless channel H. In the example shown in Fig. 7, the packet PA is transferred from the queue 14A to the backup queue 14H, and the distribution destination of the packet PA is switched from the queue 14A to the backup queue 14H. In this way, the wireless channel is switched from the wireless channel A, for which the occurrence of the switching reason has been detected, to the backup wireless channel H.

[0040] 8 is a diagram illustrating the effect of the wireless communication method of the second embodiment compared to the wireless communication method of the first embodiment. In both the wireless communication method of the first embodiment and the wireless communication method of the second embodiment, the wireless channel in which a switching event occurs is designated as wireless channel A.

[0041] First, the effects of the wireless communication method of the first embodiment will be described. The upper part of Fig. 8 shows each queue 14A at the time when a failure occurs and at the time when the failure is detected in the wireless communication method of the first embodiment, and the packet transmission history on wireless channel A and backup wireless channel H after the failure occurs. According to the wireless communication method of the first embodiment, when a failure is detected, all packets in the backup queue 14H other than packets copied from wireless channel A are discarded, and all packets in the queue 14A are moved to the backup queue 14H.

[0042] 8, when a failure occurs, packets up to #2A have been transmitted on wireless channel A. Then, when the failure is detected, packets #5A and onward in queue 14A are moved to the backup queue 14H, and packets #5A and onward are transmitted on backup wireless channel H. In this way, according to the wireless communication method of the first embodiment, the influence of packet discarding when switching wireless channels can be suppressed. However, as long as there is a time lag between the time when the failure occurs and the time when the failure is detected, it is not possible to recover all of the packets discarded on wireless channel A during that time on the backup wireless channel H.

[0043] Next, the effects of the wireless communication method of the second embodiment will be described. The lower part of Fig. 8 shows the queue 14A and the sub-queue 18A at the time when a failure is detected by the wireless communication method of the second embodiment, and the packet transmission history on wireless channel A and backup wireless channel H after the failure occurs. According to the wireless communication method of the second embodiment, when a failure is detected, all packets in the backup queue 14H other than those copied from wireless channel A are discarded, and all packets in the sub-queue 18A are moved to the backup queue 14H.

[0044] 8 , packets up to #2A have been transmitted on wireless channel A when a failure occurs. Then, packets #3A and onward from the subqueue 18A at the time the failure is detected are moved to the backup queue 14H, and packets #3A and onward are transmitted on the backup wireless channel H. As described above, according to the wireless communication method of the second embodiment, packets are transferred from the subqueue 18A, which is deeper than the queue 14A, so that packets #3A and #4A, which were scheduled to be transmitted on wireless channel A before switching to the backup wireless channel H, can also be transmitted on the backup wireless channel H. Therefore, according to the wireless communication method of the second embodiment, the influence of packet discarding when switching wireless channels can be further reduced compared to the wireless communication method of the first embodiment.

[0045] In the example shown in Figure 8, the time lag between the occurrence of a failure and its detection is two packets, and the difference in the depth of the sub-queue 18A relative to the queue 14A is also two packets. However, this is merely an example, and the depth of the sub-queues 18A-18G relative to the queues 14A-14G can be set arbitrarily by design. Furthermore, since the time lag between the occurrence of a switching event and its detection varies depending on the situation, the depth of the sub-queues 18A-18G relative to the queues 14A-14G may be shorter or longer than the time lag. In any case, according to the wireless communication method of the second embodiment, by providing sub-queues 18A-18G for each of the wireless channels A-G, the impact of packet discarding when switching wireless channels can be further reduced.

[0046] 3. Configuration of the Transmitting Device Next, an example of the configuration of the transmitting device 10 for implementing the wireless communication method of the first embodiment will be described with reference to FIG.

[0047] The transmitting device 10 constituting the wireless communication system 1 of the first embodiment has a configuration corresponding to seven wireless channels A to G and one spare wireless channel H. The transmitting device 10 includes a monitoring control unit 11, a user interface 12, a total queue 13, channel-specific queues 14, a channel-specific modulation unit 15, a channel-specific RF unit 16, and a transmitting antenna 17. The user interface 12 is used for data input by a user. The total queue 13 distributes user data packets input to the user interface 12 evenly among the queues of the seven wireless channels A to G.

[0048] The channel-specific queues 14 refer to a set of seven queues corresponding to the wireless channels A to G and a spare queue corresponding to the spare wireless channel H. The channel-specific queues 14 perform packet transfer, buffering, and queuing. The channel-specific queues 14 also copy packets from the queues for the wireless channels A to G to the queue for the spare wireless channel H, and perform channel switching processing when a switching event occurs.

[0049] The channel-specific modulation section 15 is composed of eight modulation units corresponding to the seven queues and spare queue of the channel-specific queue 14. The channel-specific modulation section 15 performs modulation processing for each radio channel.

[0050] The channel-specific RF section 16 is composed of eight RF units corresponding to the eight modulation units of the channel-specific modulation section 15. The channel-specific RF section 16 performs filtering, amplification, and monitoring for each radio channel on the signal modulated by the channel-specific modulation section 15. The signal processed for each radio channel by the channel-specific RF section 16 is transmitted from a transmission antenna 17.

[0051] The monitoring and control unit 11 performs wireless channel switching control and traffic control for the transmitting device 10. The overall queue 13, the channel-specific queues 14, the channel-specific modulation units 15, and the channel-specific RF units 16 are monitored and controlled by the monitoring and control unit 11. If a failure occurs in any of these, an alarm is notified to the monitoring and control unit 11. The monitoring and control unit 11 detects the occurrence of the failure from the alarm notification and performs control according to the nature of the failure. For example, if the channel-specific modulation unit 15 notifies the monitoring and control unit 11 of a failure in the modulation unit of wireless channel C, the monitoring and control unit 11 controls the overall queue 13, the channel-specific queues 14, the channel-specific modulation units 15, and the channel-specific RF units 16 to switch wireless channel C to the backup wireless channel H. The monitoring and control unit 11 also performs transmission and reception synchronization control and traffic distribution control with the receiving device 20. The transmission and reception synchronization control is performed, for example, when switching wireless channels.

[0052] The configuration of the transmitting device 10 for implementing the wireless communication method of the second embodiment is not shown in the drawings. When implementing the wireless communication method of the second embodiment, in addition to the seven queues corresponding to the wireless channels A to G and the spare queue corresponding to the spare wireless channel H, seven sub-queues corresponding to the wireless channels A to G may be provided in the channel-specific queue 14. The method of using the sub-queues is as explained in the explanation of the second embodiment.

[0053] 4. Configuration of the Receiving Device Next, an example of the configuration of the receiving device 20 for implementing the wireless communication method of the first embodiment and the wireless communication method of the second embodiment will be described with reference to Fig. 10. Unlike the transmitting device 10, the configuration of the receiving device 20 can be made common between the wireless communication method of the first embodiment and the wireless communication method of the second embodiment.

[0054] The receiving device 20 constituting the wireless communication system 1 of the first embodiment or the wireless communication system 2 of the second embodiment has a configuration corresponding to seven wireless channels A to G and one spare wireless channel H. The receiving device 20 includes a monitoring control unit 21, a user interface 22, an overall queue 23, a channel-specific deframing unit 24, a channel-specific demodulation unit 25, a channel-specific RF unit 26, and a receiving antenna 27.

[0055] The channel-specific RF section 26 is composed of eight RF units corresponding to the seven radio channels A to G and one spare radio channel H. In the channel-specific RF section 26, amplification processing, filtering processing, automatic gain processing, and C / N monitoring processing are performed on the signal received by the receiving antenna 27 for each radio channel.

[0056] The channel-specific demodulation section 25 is composed of eight demodulation units corresponding to the eight RF units of the channel-specific RF section 26. The channel-specific demodulation section 25 performs sub-modulation processing and monitors the bit error rate for each wireless channel.

[0057] The channel-specific deframing section 24 is composed of eight deframing units corresponding to the eight demodulation units of the channel-specific demodulation section 25. The channel-specific deframing section 24 performs deframing, packet transfer, and buffering. The channel-specific deframing section 24 also performs channel switching processing when a switching event occurs. For this reason, the seven deframing units corresponding to radio channels A to G are independent of each other, but the deframing unit corresponding to spare radio channel H is connected to the other seven deframing units.

[0058] The overall queue 23 is connected to eight deframing units of the channel-specific deframing section 24. In the overall queue 23, buffering, mapping, and scheduling are performed on packets transferred from the channel-specific deframing section 24. The packets integrated in the overall queue 23 are sent as user data to the user interface 22. The user interface 22 is used to output data to the user.

[0059] The monitoring and control unit 21 executes wireless channel switching control and traffic control for the receiving device 20. The overall queue 23, the channel-specific deframing unit 24, the channel-specific demodulation unit 25, and the channel-specific RF unit 26 are subject to monitoring and control by the monitoring and control unit 21. If a failure occurs in any of these, an alarm is notified to the monitoring and control unit 21. The monitoring and control unit 21 detects the occurrence of the failure from the alarm notification and performs control according to the nature of the failure. The monitoring and control unit 21 also executes synchronization control of transmission and reception and traffic distribution control with the transmitting device 10.

[0060] 5. Hardware Configuration of Wireless Communication System Next, a hardware configuration common to both the wireless communication system 1 of the first embodiment and the wireless communication system 2 of the second embodiment will be described with reference to Fig. 11. As described above, each of the wireless communication systems 1 and 2 includes a transmitting device 10 and a receiving device 20.

[0061] 11 , the transmitting device 10 includes a processor 101, a memory 102, a wireless communication module 104, a wired communication module 105, a user interface 12, and a transmitting antenna 17. These elements constituting the transmitting device 10 are wiredly coupled. The wireless communication module 104 is provided for digital wireless communication with the receiving device 20. The aforementioned channel-specific modulation unit 15 and channel-specific RF unit 16 are provided in the wireless communication module 104. The wired communication module 105 is provided for wired communication with a wired network. The transmitting device 10 may be configured to transmit data received from an external device via the wired communication module 105 to the receiving device 20 via the wireless communication module 104.

[0062] The processor 101 may be a CPU, RISC, DSP, FPGA, ASIC, PLD, or another processing unit, a combination of two or more thereof, or a dedicated processor for the transmitting device. The processor 101 may be communicatively coupled to the memory 102 or may include the memory 102. The memory 102 includes RAM, ROM, and storage. The memory 102 stores one or more programs executable by the processor 101. At least one program includes a plurality of instructions 103 for causing the processor 101 to execute the wireless communication method of the first or second embodiment. The overall queue 13 and the channel-specific queues 14 are implemented in software by the processor 101 executing the instructions 103. The transmitting device 10 may include a plurality of processors 101 and a plurality of memories 102.

[0063] The transmitting device 10 also includes a drive (not shown). The drive includes a computer-readable recording medium. The storage medium can be used to store a program. The program may be provided to the transmitting device 10 via a network.

[0064] 11 , the receiving device 20 includes a processor 201, a memory 202, a wireless communication module 204, a wired communication module 205, a user interface 22, and a receiving antenna 27. These elements constituting the receiving device 20 are wiredly coupled. The wireless communication module 204 is provided for digital wireless communication with the receiving device 20. The aforementioned channel-specific demodulation unit 25 and channel-specific RF unit 26 are provided in the wireless communication module 204. The wired communication module 205 is provided for wired communication with a wired network. The receiving device 20 may be configured to transmit data received from the transmitting device 10 via the wireless communication module 204 to an external device via the wired communication module 205.

[0065] The processor 201 may be a CPU, RISC, DSP, FPGA, ASIC, PLD, or another processing unit, a combination of two or more thereof, or a dedicated processor for the receiving device. The processor 201 may be communicatively coupled to the memory 202 or may include the memory 202. The memory 202 stores one or more programs executable by the processor 201. At least one program includes a plurality of instructions 203 for causing the processor 201 to execute the wireless communication method of the first or second embodiment. The overall queue 23 and the channel-specific deframing unit 24 are implemented in software by the processor 201 executing the instructions 203. The receiving device 20 may include a plurality of processors 201 and a plurality of memories 202.

[0066] The receiving device 20 also includes a drive (not shown). The drive includes a computer-readable recording medium. The storage medium can be used to store a program. The program may be provided to the receiving device 20 via a network.

[0067] 6. Hardware Configuration of Wireless Communication System Finally, the system operation common to both the wireless communication system 1 of the first embodiment and the wireless communication system 2 of the second embodiment will be described with reference to Fig. 12. Fig. 12 is a flow diagram showing an example of the flow of system operation.

[0068] In step S101, a spare wireless channel is utilized to copy and transmit a portion of packets from each working wireless channel, with packets from each wireless channel being evenly copied to the spare wireless channel in a round-robin fashion.

[0069] In step S111, it is determined whether a line disconnection has occurred in any of the wireless channels due to a wireless device failure. The wireless devices referred to here include the wireless communication modules of the transmitting device 10 and the receiving device 20. If the result of the determination in step S111 is negative, a determination is made in step S121. In step S121, it is determined whether quality degradation has occurred in any of the wireless channels. If the result of the determination in step S121 is negative, the wireless communication system is considered to be in a normal state, and the flow returns to the beginning.

[0070] If it is determined in step S111 that a line disconnection has occurred due to a wireless device failure, steps S112, S113, and S114 are executed. First, in step S112, timing is synchronized between transmission and reception using a control signal from the receiving device 20 to the transmitting device 10, and packets on the failed wireless channel are switched to the backup wireless channel. Next, in step S113, repair measures are taken to fix the device failure. In step S114, it is determined whether the line has recovered from the line disconnection. Then, repair measures are continued until the line has recovered from the line disconnection, and when the line has recovered from the line disconnection, step S131 is executed.

[0071] On the other hand, if it is determined in step S121 that quality degradation has occurred in the wireless channel, steps S122, S123, and S124 are executed. First, in step S122, timing is adjusted between transmission and reception using a control signal from the receiving device 20 to the transmitting device 10, and packets on the wireless channel with deteriorated quality are switched to the backup wireless channel. Next, in step S123, the receiving device 20 monitors the line quality using the bit error rate and C / N ratio. In step S124, it is determined whether the quality has recovered. Then, monitoring is continued until the quality has recovered, and when the quality has recovered, step S131 is executed.

[0072] In step S131, the timing between the transmitter and the receiver is adjusted by a control signal from the receiver 20 to the transmitter 10, and the radio channel is switched back from the backup radio channel to the original radio channel.

[0073] 7. Others The wireless communication method disclosed herein can be used in a wide range of applications, including terrestrial fixed microwave communications, FWA, satellite communications, wireless LAN, millimeter wave band communications, quasi-millimeter wave band communications, and mobile communications. Furthermore, the wireless communication method disclosed herein can be applied not only to frequency division duplex systems but also to time division duplex systems.

[0074] 1, 2 Wireless communication system 10 Transmitter 20 Receiver 14A-14G Queue 14H Reserve queue 18A-18G Sub-queue CA-CG Wireless channel CH Reserve wireless channel PA-PG Packet

Claims

1. A wireless communication method using multiple wireless channels and at least one spare wireless channel, comprising: distributing packets to be transmitted to multiple queues corresponding to the multiple wireless channels; copying a portion of the packets to be transmitted on the multiple wireless channels to a spare queue corresponding to the at least one spare wireless channel in an equal ratio among the multiple wireless channels; and, upon the occurrence of a switching reason in any of the multiple wireless channels, switching from transmitting packets from the wireless channel having the switching reason to transmitting packets from the at least one spare wireless channel.

2. A wireless communication method according to claim 1, further comprising: discarding packets in the reserve queue other than packets copied from the wireless channel having the switching reason; and transferring all packets in the queue corresponding to the wireless channel having the switching reason to the reserve queue.

3. A wireless communication method according to claim 2, further comprising the steps of discarding packets other than the packets copied from the wireless channel having the switching reason and transferring all packets in the queue corresponding to the wireless channel having the switching reason to the spare queue at the timing when the occurrence of the switching reason is detected.

4. A wireless communication method as claimed in claim 1, further comprising: copying packets identical to the packets distributed to the queue to a sub-queue deeper than the queue provided for each of the multiple wireless channels; discarding packets in the backup queue other than the packets copied from the wireless channel having the switching reason; and transferring all packets in the sub-queue corresponding to the wireless channel having the switching reason to the backup queue.

5. A wireless communication method according to claim 4, further comprising the steps of discarding packets other than the packets copied from the wireless channel having the switching reason, and transferring all packets in the sub-queue corresponding to the wireless channel having the switching reason to the reserve queue at the timing when the occurrence of the switching reason is detected.

6. A wireless communication system having a plurality of wireless channels and at least one spare wireless channel, comprising: at least one processor; at least one memory coupled to the at least one processor or incorporated in the at least one processor; and a plurality of instructions stored in the at least one memory and executable by the at least one processor, wherein the plurality of instructions are configured to cause the at least one processor to execute the following: distributing packets to be transmitted to a plurality of queues corresponding to the plurality of wireless channels; copying a portion of packets to be transmitted on the plurality of wireless channels to a spare queue corresponding to the at least one spare wireless channel in equal proportions among the plurality of wireless channels; and, upon the occurrence of a switching reason in any of the plurality of wireless channels, switching from transmission of packets from the wireless channel having the switching reason to transmission of packets from the at least one spare wireless channel.

7. A transmitting device for transmitting packets using multiple wireless channels and at least one spare wireless channel, comprising: at least one processor; at least one memory coupled to the at least one processor or built into the at least one processor; and a plurality of instructions stored in the at least one memory and executable by the at least one processor, wherein the plurality of instructions are configured to cause the at least one processor to execute the following: distributing packets to be transmitted to a plurality of queues corresponding to the multiple wireless channels; copying a portion of packets to be transmitted on the multiple wireless channels to a spare queue corresponding to the at least one spare wireless channel in equal proportions among the multiple wireless channels; and, upon the occurrence of a switching reason in any of the multiple wireless channels, switching from transmission of packets from the wireless channel having the switching reason to transmission of packets from the at least one spare wireless channel.

8. A program for causing a transmitting device to transmit packets using multiple wireless channels and at least one spare wireless channel, the program including multiple instructions executable by at least one processor of the transmitting device, the multiple instructions being configured to cause the at least one processor to execute the following: distributing packets to be transmitted to multiple queues corresponding to the multiple wireless channels; copying a portion of the packets to be transmitted on the multiple wireless channels to a spare queue corresponding to the at least one spare wireless channel in equal proportions among the multiple wireless channels; and, upon the occurrence of a switching reason for any of the multiple wireless channels, switching from transmission of packets from the wireless channel having the switching reason to transmission of packets from the at least one spare wireless channel.

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