Remote radio device and communication method for a remote radio device

Abstract

To provide a remote radio device and a communication method for a remote radio device for transmitting / receiving signals to / from a base radio device in a transmission reception period.SOLUTION: A radio communication system 10 comprising one computer 12 and at least one communication network 14 comprises a remote radio device 18 for transmitting / receiving signals to / from a base radio device 16 in a transmission reception period, the remote radio device comprising: a transmission / reception processing unit 44 for executing signal transmission processing in each of a plurality of continuous transmission reception periods until transmission to the base radio device 16 is successful; a counting unit 46 for counting the number of times of execution of the transmission processing; a transmission selection unit 48 that when a count value N of the counting unit is equal to or larger than a predetermined number of times, selects whether to execute the transmission processing or to stand by in the next transmission reception period according to a predetermined rule; and a transmission prohibition unit 50 that when standing by is selected by the transmission selection unit 48, prohibits the transmission / reception processing unit 44 from performing the transmission processing.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a remote radio device that transmits and receives signals to and from a base radio device in a transmission / reception cycle, and a communication method for the remote radio device. [Background technology]

[0002] Patent Document 1 discloses an industrial wireless communication system including a computer and multiple communication networks. The computer manages and controls multiple robots and the like. Each communication network includes one base wireless device and multiple remote wireless devices. The base wireless device is connected to the computer. Meanwhile, the remote wireless devices are connected to sensors and actuators. The sensors and actuators are provided on the robots and the like. For example, the base wireless device transmits signals to each remote wireless device to instruct the actuator to operate. Meanwhile, each remote wireless device transmits signals indicating the sensor detection results and the like to the base wireless device. In the wireless communication system of Patent Document 1, the base wireless device and the multiple remote wireless devices hop frequencies at a predetermined period. This prevents radio wave interference between the base wireless device and surrounding wireless devices. Similarly, frequency hopping also prevents radio wave interference between the remote wireless devices and surrounding wireless devices. The frequency hopping period is called the transmission / reception period. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-188868 Summary of the Invention [Problem to be solved by the invention]

[0004] In the communication network of Patent Document 1, multiple remote radio devices perform frequency hopping using the same hopping pattern and the same transmission / reception cycle. Therefore, collisions between signals transmitted by each remote radio device are likely to occur. When signals collide, each remote radio device retransmits the signal. In such a case, if each remote radio device continuously retransmits a signal of the same frequency at the same cycle, signal collisions occur repeatedly. This results in a long time for each remote radio device to complete transmission. As a result, the communication speed of the wireless communication system decreases, and the processing capacity of a robot or the like decreases.

[0005] The present invention aims to solve the above-mentioned problems. [Means for solving the problem]

[0006] One aspect of the present invention is a remote radio device that transmits and receives signals with a base radio device in a transmission / reception cycle, and includes a transmission / reception processing unit that performs signal transmission processing in each of multiple consecutive transmission / reception cycles until transmission to the base radio device is successful, a counting unit that counts the number of times the transmission processing is performed, a transmission selection unit that, if the count value of the counting unit is equal to or greater than a predetermined number, selects whether to perform the transmission processing in the next transmission / reception cycle or to wait in accordance with a predetermined rule, and a transmission prohibition unit that, if waiting is selected by the transmission selection unit, prohibits the transmission processing by the transmission / reception processing unit.

[0007] Another aspect of the present invention is a communication method for a remote radio device that transmits and receives signals with a base radio device in a transmission / reception cycle, comprising: a transmission / reception processing step that executes a signal transmission process in each of a plurality of consecutive transmission / reception cycles until transmission to the base radio device is successful; a counting step that counts the number of times the transmission process is executed; a transmission selection step that, if the count value of the counting step is equal to or greater than a predetermined number, selects whether to execute the transmission process or wait in the next transmission / reception cycle in accordance with a predetermined rule; and a transmission prohibition step that prohibits the transmission process if wait is selected in the transmission selection step. [Effects of the Invention]

[0008] According to the present invention, it is possible to reduce the number of collisions of signals transmitted to the base radio unit. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating a configuration of a wireless communication system. [Figure 2] FIG. 2 is a diagram illustrating functional blocks of the wireless communication system according to the first embodiment. [Figure 3] 4 is a flowchart showing a main process of the first embodiment. [Figure 4] 10 is a flowchart showing a transmission process. [Figure 5] FIG. 2 is a diagram illustrating an example of a transmission format in the first embodiment. [Figure 6] FIG. 10 is a diagram illustrating functional blocks of a wireless communication system according to a second embodiment. [Figure 7] 10 is a flowchart showing transmission slots in one transmission / reception period. [Figure 8] 10 is a flowchart showing a main process of a second embodiment. [Figure 9] FIG. 10 is a diagram illustrating an example of a transmission form in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] [1 First Embodiment] [1-1 Wireless Communication System 10] Fig. 1 is a diagram showing the configuration of a wireless communication system 10. Fig. 2 is a diagram showing functional blocks of the wireless communication system 10 of the first embodiment. The industrial wireless communication system 10 includes one computer 12 and at least one communication network 14. One communication network 14 includes one base wireless device 16 and multiple remote wireless devices 18. The industrial facility is provided with one or more robots, etc. (not shown).

[0011] The computer 12 monitors and controls one or more robots, etc. The computer 12 may include, for example, a PLC (Programmable Logic Controller). The computer 12 includes an interface (not shown) for transmitting and receiving data via wire or wirelessly. The computer 12 transmits signals to the base radio device 16 via the interface. The computer 12 also receives signals transmitted from the base radio device 16 via the interface.

[0012] One or more robots or the like are equipped with actuators and sensors. The actuators operate according to instructions from the computer 12. The sensors detect the operation of the robots. In this specification, the sensors and actuators are collectively referred to as S / A 20. The actuators receive control signals transmitted from the computer 12 via the base radio device 16 and the remote radio device 18. The sensors transmit sensor signals indicating the detection results to the computer 12 via the base radio device 16 and the remote radio device 18.

[0013] [1-2 Base Radio Equipment 16] As shown in FIG. 2, the base radio device 16 includes a base calculation unit 22, a base storage unit 24, a base communication unit 26, and a base interface .

[0014] The base computing unit 22 has a processing circuit. The processing circuit may be a processor such as a CPU. The processing circuit may be an integrated circuit such as an ASIC or FPGA. The processor has various functions by executing programs stored in the base storage unit 24. For example, the base computing unit 22 performs a process of receiving signals from the computer 12 using the base interface 28. The base computing unit 22 also performs a process of transmitting signals to the computer 12 using the base interface 28. The base computing unit 22 also performs a process of receiving signals from multiple remote radio devices 18 using the base communication unit 26. The base computing unit 22 also performs a process of transmitting signals to multiple remote radio devices 18 using the base communication unit 26. The base computing unit 22 also switches the frequency of the channel used for communication with the remote radio devices 18 based on the hopping information.

[0015] The base storage unit 24 has a volatile memory and a non-volatile memory. Examples of the volatile memory include RAM. Examples of the non-volatile memory include ROM and flash memory. The volatile memory stores, for example, data acquired from the outside and data calculated by the base calculation unit 22. The non-volatile memory stores, for example, predetermined programs and predetermined numerical values. The base storage unit 24 stores hopping information that is common to the remote radio device 18. The hopping information includes information on hopping patterns and information on transmission and reception cycles. At least a part of the base storage unit 24 may be provided in the processor, integrated circuit, etc. as described above.

[0016] The base communication unit 26 has a communication circuit. The communication circuit includes a transmitting circuit and a receiving circuit. The base communication unit 26 transmits signals to the remote radio device 18. The base communication unit 26 also receives signals transmitted by the remote radio device 18.

[0017] The base interface 28 has an input / output interface for wired communication with the computer 12 .

[0018] [1-3 Remote Radio Device 18] As shown in FIG. 2, the remote wireless device 18 includes a remote computing unit 32, a remote storage unit 34, a remote communication unit 36, and a remote interface 38.

[0019] The remote calculation unit 32 has a processing circuit. The processing circuit may be a processor such as a CPU. The processing circuit may be an integrated circuit such as an ASIC or FPGA. The remote calculation unit 32 has various functions by executing programs stored in the base storage unit 24. For example, the remote calculation unit 32 functions as a frequency switching unit 42, a transmission / reception processing unit 44, a counting unit 46, a transmission selection unit 48, a transmission prohibition unit 50, and an input / output control unit 52.

[0020] Based on the hopping information, the frequency switching unit 42 switches the frequency of the channel used by the remote communication unit 36. The hopping information is stored in the remote storage unit 34 in advance.

[0021] The transmission / reception processing unit 44 performs processing to transmit signals to the base radio device 16 using the transmission circuit of the remote communication unit 36. The transmission / reception processing unit 44 also performs processing to receive signals transmitted by the base radio device 16 using the reception circuit of the remote communication unit 36. The transmission / reception processing unit 44 transmits one packet signal in one transmission / reception cycle. When transmitting one packet signal, the transmission / reception processing unit 44 performs a series of transmission processing (FIG. 4). The transmission processing includes clear channel assessment (CCA), processing to transmit a signal, and processing to receive an acknowledgement (ACK) transmitted from the base radio device 16.

[0022] The counting unit 46 counts the number of transmission processes executed from the start of transmission of one packet of signal until the transmission is successful.

[0023] The transmission selection unit 48 selects whether the count value N of the count unit 46 reaches a predetermined number of times. The aboveIn this case, the transmission selection unit 48 selects whether to execute transmission processing or wait in the next transmission / reception cycle. The transmission selection unit 48 makes the selection according to a predetermined rule. The predetermined rule is stored in the remote storage unit 34. The predetermined rule may be information that determines the selection order between transmission and wait. The predetermined rule may also be an algorithm for randomly making the selection, such as an algorithm for generating a pseudo-random number sequence.

[0024] The transmission prohibition unit 50 prohibits the transmission processing by the transmission / reception processing unit 44 when the transmission selection unit 48 selects standby.

[0025] The input / output control unit 52 uses the remote interface 38 to perform a process of transmitting a control signal to the S / A 20. The input / output control unit 52 also uses the remote interface 38 to perform a process of receiving a sensor signal transmitted by the S / A 20.

[0026] The remote storage unit 34 has a volatile memory and a non-volatile memory. Examples of the volatile memory include RAM. Examples of the non-volatile memory include ROM and flash memory. The volatile memory stores, for example, data acquired from the outside and data calculated by the remote calculation unit 32. The non-volatile memory stores, for example, predetermined programs and predetermined numerical values. The remote storage unit 34 stores hopping information that is common to the base radio device 16. The hopping information includes information on hopping patterns and information on transmission and reception cycles. At least a part of the remote storage unit 34 may be provided in the processor, integrated circuit, etc. as described above.

[0027] The remote communication unit 36 ​​has a communication circuit. The communication circuit includes a transmitting circuit and a receiving circuit. The remote communication unit 36 ​​transmits signals to the base radio device 16. The remote communication unit 36 ​​also receives signals transmitted by the base radio device 16.

[0028] The remote interface 38 has an input / output interface for performing wired communication with the S / A 20. The remote interface 38 may also have a wireless interface for performing short-range wireless communication with the S / A 20.

[0029] [1-4 Processing performed by the remote radio device 18] [A Main Processing] The main processing executed by the remote radio device 18 when transmitting a signal will now be described. FIG. 3 is a flowchart showing the main processing of the first embodiment. The remote calculation unit 32 executes the main processing shown in FIG. 3 for each transmission / reception cycle. Before the first execution of the main processing, the count unit 46 sets the count value N to zero. The count value N indicates the number of transmission processes executed from the start of transmission of one packet of signal until the transmission is successful.

[0030] In step S1, the frequency switching unit 42 switches the channel frequency in accordance with the hopping pattern stored in the remote storage unit 34. When step S1 ends, the process proceeds to step S2.

[0031] In step S2, the transmission / reception processing unit 44 determines whether there is information (transmission information) to be transmitted to the computer 12. The transmission information may be, for example, a sensor signal acquired from the S / A 20. If there is transmission information (step S2: YES), the process proceeds to step S3. On the other hand, if there is no transmission information (step S2: NO), the process for this transmission / reception cycle ends.

[0032] In step S3, the counting unit 46 compares the count value N with a predetermined number of times (here, five times). The predetermined number of times is the upper limit of the number of times the transmission process is executed consecutively. The predetermined number of times is stored in advance in the remote storage unit 34. When the count value N is equal to or greater than the predetermined number of times, less than If the count value N is equal to or greater than the predetermined number of times (step S3: YES), the process proceeds to step S4. The above If so (step S3: NO), the process proceeds to step S7.

[0033] When the process moves to step S4 from step S3 or step S8 (described later), the transmission / reception processing unit 44 executes the transmission process shown in Fig. 4. In the transmission process, the transmission / reception processing unit 44 executes a series of processes for transmitting a signal indicating transmission information to the base radio device 16. When step S4 ends, the process moves to step S5.

[0034] In step S5, the transmission / reception processing unit 44 determines whether the signal transmission was successful in the transmission process executed in step S4. If the signal transmission was successful (step S5: YES), the process proceeds to step S6. On the other hand, if the signal transmission failed (step S5: NO), the process proceeds to step S9.

[0035] In step S6, the counter 46 clears the count value N. When step S6 is completed, the process in which the remote radio device 18 transmits one packet of signals is completed.

[0036] When the process moves from step S3 to step S7, the transmission selection unit 48 selects whether to execute the transmission process or to wait without executing the transmission process. The transmission selection unit 48 makes the selection according to a predetermined rule. When step S7 ends, the process moves to step S8.

[0037] If the transmission selection unit 48 selects transmission (step S8: transmission), the process proceeds to step S4. In this case, the transmission and reception processing unit 44 executes the transmission process shown in FIG. 4. On the other hand, if the transmission selection unit 48 selects standby (step S8: standby), the transmission prohibition unit 50 prohibits transmission processing in the current transmission and reception cycle. Furthermore, the transmission and reception processing unit 44 waits without executing transmission processing. In other words, the remote radio device 18 gives the opportunity to transmit a signal to the base radio device 16 to another remote radio device 18. In this case, if one remote radio device 18 executes transmission processing, the signal transmission from that remote radio device 18 to the base radio device 16 will be successful.

[0038] When the process moves from step S5 to step S9, the counting unit 46 adds 1 to the count value N. After step S9 is completed, the process for the current transmission / reception cycle ends.

[0039] [B Transmission Processing] Fig. 4 is a flowchart showing the transmission process. In step S4 of the main process shown in Fig. 3, the processes of steps S11 to S17 described below are performed. The transmission process described below includes CCA, signal transmission, and reception and confirmation of ACK transmitted from the base radio device 16.

[0040] In step S11, the transmission / reception processing unit 44 performs CCA. The transmission / reception processing unit 44 detects radio waves using the same frequency as the frequency of the currently selected channel. When step S11 is completed, the process proceeds to step S12.

[0041] In step S12, the transmission / reception processing unit 44 determines whether the frequency of the own channel is in use based on the result of CCA execution. If the frequency of the own channel is not in use (step S12: NO), the process proceeds to step S13. On the other hand, if the frequency of the own channel is in use (step S12: YES), the process proceeds to step S17.

[0042] In step S13, the transmission / reception processing unit 44 uses the remote communication unit 36 ​​to transmit a signal indicating the transmission information to the base radio device 16. When step S13 ends, the process proceeds to step S14.

[0043] In step S14, the transmission / reception processing unit 44 waits for an ACK transmitted from the base radio device 16, with the upper limit time as the limit. When the remote communication unit 36 ​​receives the ACK, the transmission / reception processing unit 44 detects the ACK. At this time, the transmission / reception processing unit 44 confirms that the ACK has been received. The upper limit time is determined by the transmission / reception cycle, i.e., the frequency hopping cycle. The transmission / reception processing unit 44 sets the remaining time until the timing of switching to the next frequency as the upper limit time. When step S14 is completed, the process proceeds to step S15.

[0044] In step S15, the transmission and reception processing unit 44 determines whether or not an ACK has been detected. If the transmission and reception processing unit 44 has detected an ACK (step S15: YES), the process proceeds to step S16. On the other hand, if the transmission and reception processing unit 44 has not detected an ACK (step S15: NO), the process proceeds to step S17.

[0045] In step S16, the transmission / reception processing unit 44 determines that the transmission was successful. When step S16 ends, the process proceeds to step S5 shown in FIG.

[0046] On the other hand, when the process moves from step S12 or step S15 to step S17, the transmission / reception processing unit 44 determines that the transmission has failed. When step S17 ends, the process moves to step S5 shown in FIG.

[0047] [1-5 Example of transmission format] Fig. 5 is a diagram showing an example of a transmission mode in the first embodiment. Fig. 5 shows a situation in which a signal collision occurs as a result of the four remote radio devices 18 shown in Fig. 1 simultaneously performing transmission processing to the base radio device 16. Here, the four remote radio devices 18 are referred to as remote radio device 18(A) to remote radio device 18(D).

[0048] (A) to (D) in Fig. 5 show remote radio devices 18(A) to 18(D). 1st, 2nd, ..., 10th in Fig. 5 indicate the first, second, ..., 10th transmission / reception cycles that arrive after the generation of transmission information in each remote radio device 18. The first to tenth transmission / reception cycles are consecutive. Black squares indicate that the transmission / reception processing unit 44 has executed transmission processing. White squares indicate that the transmission / reception processing unit 44 has waited without executing transmission processing.

[0049] The transmission / reception processing unit 44 of the remote radio devices 18(A) to 18(D) receives the count value N when the count value N is 5. That's all. Until the fifth transmission / reception cycle is completed, signal collisions occur and signal transmissions by the remote radio devices 18(A) to 18(D) fail. The transmission / reception processing unit 44 of the remote radio devices 18(A) to 18(D) executes the transmission process at each transmission / reception cycle until the fifth transmission / reception cycle is completed. That's all. After that, the remote radio devices 18 either execute a transmission process or wait without executing a transmission process. In the transmission mode shown in Fig. 5, in the sixth transmission / reception cycle, only the remote radio device 18(C) executes a transmission process. Meanwhile, the remote radio devices 18(A), 18(B), and 18(D) wait. At this time, no signal collision occurs. Therefore, the signal transmission by the remote radio device 18(C) is successful. Similarly, if only one remote radio device 18 executes a transmission process, the transmission by that remote radio device 18 is successful.

[0050] If there is a remote radio device 18 connected to a frequently used S / A 20, the transmission selection unit 48 of the remote radio device 18 may use a predetermined rule that makes it easier to select transmission. With this configuration, the transmission information of the frequently used S / A 20 is more likely to be transmitted to the base radio device 16.

[0051] As described above, according to the first embodiment, each remote radio device 18 negotiates with another remote radio device 18 for transmission opportunities, thereby reducing the number of collisions of signals transmitted to the base radio device 16. This makes it easier for each remote radio device 18 to successfully transmit a signal at an early stage. As a result, a decrease in the communication speed of the communication network 14 due to signal collisions is suppressed.

[0052] [2 Second Embodiment] Similar to the first embodiment, the communication network 14 of the second embodiment is also provided in the industrial wireless communication system 10. The remote wireless device 18 of the second embodiment has the function of selecting a transmission slot 56 (FIG. 7) in addition to the functions of the remote wireless device 18 of the first embodiment.

[0053] [2-1 Remote Radio Device 18] 6 is a diagram showing functional blocks of the wireless communication system 10 of the second embodiment. The remote wireless device 18 of the second embodiment has the entire configuration of the remote wireless device 18 of the first embodiment. Of the configuration of the remote wireless device 18 of the second embodiment, the configuration common to the remote wireless device 18 of the first embodiment is assigned the same reference numerals as in the first embodiment. In the second embodiment, the remote calculation unit 32 also functions as a slot selection unit 54.

[0054] 7, one transmission / reception cycle includes a transmission time t1, a reception time t2, and other times not shown (such as the time required for switching between transmission and reception). The transmission time t1 is a time frame used by the transmission / reception processing unit 44 when transmitting a signal. For example, the transmission time t1 is 2100 [μsec]. The reception time t2 is a time frame used by the transmission / reception processing unit 44 when receiving an ACK transmitted from the base radio device 16. For example, the reception time t2 is 1300 [μsec]. The transmission time t1 is set to a time longer than the time required for the transmission / reception processing unit 44 to perform CCA and transmit one packet signal.

[0055] The slot selector 54 provides multiple transmission slots 56 with different start timings for the transmission process during the transmission time t1. For example, as shown in FIG. 7, the slot selector 54 provides multiple transmission slots 56 with different start timings corresponding to the CCA time. If the transmission time t1 is 2100 μsec, the time required for CCA is 200 μsec, and the time required to transmit one packet signal is 1300 μsec, the slot selector 54 can provide four transmission slots 56 during the transmission time t1. The slot selector 54 can change the number of transmission slots 56 provided during the transmission time t1 depending on the time required for CCA and the time required to transmit one packet signal. The number and start timings of the transmission slots 56 are stored in advance in the remote storage unit 34.

[0056] Furthermore, before transmission processing is performed, the slot selection unit 54 selects one transmission slot 56 from the multiple transmission slots 56 using an arbitrary method. For example, the slot selection unit 54 may select the transmission slot 56 according to a predetermined rule. The predetermined rule may be information that determines the selection order of the transmission slots 56. The predetermined rule may also be an algorithm for random selection, such as an algorithm that generates a pseudo-random number sequence. Alternatively, the slot selection unit 54 may select the transmission slot 56 according to a first rule when the count value N is less than a predetermined number of determinations, and may select the transmission slot 56 according to a second rule when the count value N is equal to or greater than the predetermined number of determinations. In this case, the first rule is information that determines the selection order of the transmission slots 56, and the second rule may be an algorithm for random selection, such as an algorithm that generates a pseudo-random number sequence. The predetermined rule, the first rule, and the second rule are pre-stored in the remote storage unit 34.

[0057] [2-2 Processing performed by the remote radio device 18] Fig. 8 is a flowchart showing the main processing of the second embodiment. The remote calculation unit 32 executes the main processing shown in Fig. 8 for each transmission / reception cycle. The main processing shown in Fig. 8 is substantially the same as the main processing shown in Fig. 3 except for the addition of the processing of step S24. In step S24, the slot selection unit 54 selects a transmission slot 56. In step S25, the transmission / reception processing unit 44 performs transmission processing using the selected transmission slot 56.

[0058] [2-3 Example of transmission format] Fig. 9 is a diagram showing an example of a transmission mode in the second embodiment. Fig. 9 shows a situation in which a signal collision occurs as a result of the four remote radio devices 18 shown in Fig. 1 simultaneously performing transmission processing to the base radio device 16. Here, the four remote radio devices 18 are referred to as remote radio device 18(A) to remote radio device 18(D).

[0059] As in FIG. 5, (A) to (D) in FIG. 9 indicate remote radio devices 18(A) to 18(D). The 1st, 2nd, ..., and 6th in FIG. 9 indicate the first, second, ..., and sixth transmission / reception cycles that arrive after the generation of transmission information in each remote radio device 18. The first to sixth transmission / reception cycles are consecutive. The four squares in each cycle indicate four transmission slots 56. The transmission timing of the four transmission slots 56 increases from left to right. Black squares indicate transmission slots 56 selected by the slot selection unit 54 and used by the transmission / reception processing unit 44. Squares marked with an X indicate transmission slots 56 not selected by the slot selection unit 54. A row of four white squares indicates that the transmission / reception processing unit 44 waited without executing transmission processing.

[0060] In the first transmission / reception cycle, the transmission / reception processing units 44 of the remote radio devices 18(A) to 18(D) perform transmission processing using the first transmission slot 56. In this case, a signal collision occurs, and the signal transmissions performed by the remote radio devices 18(A) to 18(D) fail.

[0061] In the second transmission / reception cycle, the transmission / reception processing unit 44 of the remote radio device 18(A) performs transmission processing using the first transmission slot 56. The transmission / reception processing units 44 of the remote radio devices 18(B) to 18(D) perform transmission processing using the second transmission slot 56. The transmission / reception processing units 44 of the remote radio devices 18(B) to 18(D) detect the signal from the remote radio device 18(A) using CCA. Therefore, the transmission / reception processing units 44 of the remote radio devices 18(B) to 18(D) do not transmit signals. At this time, no signal collision occurs. Therefore, the signal transmission of the remote radio device 18(A) is successful.

[0062] Further, similarly to the first embodiment, the transmission / reception processing unit 44 of the remote radio devices 18(A) to 18(D) performs the operation when the count value N is 5. That's all. After that, the transmission process is executed, or the process waits without executing the transmission process.

[0063] If there is a remote radio device 18 connected to a frequently used S / A 20, the slot selection unit 54 of the remote radio device 18 may make it easier to select the first transmission slot 56. In this case, the slot selection unit 54 may use a rule that makes it easier to select the first transmission slot 56. With this configuration, the transmission information of the frequently used S / A 20 is more likely to be transmitted to the base radio device 16.

[0064] As described above, according to the second embodiment, the transmission timing of each remote radio device 18 is shifted, thereby reducing the number of collisions of signals transmitted to the base radio device 16. This makes it easier for each remote radio device 18 to successfully transmit a signal at an early stage. As a result, a decrease in the communication speed of the communication network 14 due to signal collisions is suppressed.

[0065] [3 Technical ideas obtained from the embodiments] The technical ideas that can be understood from the above-described embodiments will be described below.

[0066] A first aspect of the present invention is a remote radio device 18 that transmits and receives signals to and from a base radio device 16 in a transmission / reception cycle, and includes a transmission / reception processing unit 44 that executes signal transmission processing in each of a plurality of consecutive transmission / reception cycles until transmission to the base radio device 16 is successful, a counting unit 46 that counts the number of times the transmission processing is executed, a transmission selection unit 48 that, when the count value N of the counting unit is equal to or greater than a predetermined number, selects whether to execute the transmission processing in the next transmission / reception cycle or to wait in accordance with a predetermined rule, and a transmission prohibition unit 50 that, when waiting is selected by the transmission selection unit 48, prohibits the transmission processing by the transmission / reception processing unit 44.

[0067] In the first aspect of the present invention, a slot selection unit 54 is provided that selects one transmission slot 56 from a plurality of transmission slots 56 that are provided within each of the transmission and reception cycles and have different start timings for the transmission processing, and the transmission and reception processing unit 44 may perform the transmission processing using the transmission slot 56 selected by the slot selection unit 54.

[0068] In the first aspect of the present invention, the transmission / reception processing unit 44 may perform the transmission processing by performing a clear channel evaluation, transmitting a signal, and receiving an acknowledgment response transmitted from the base radio device 16, and may determine that the transmission has failed if it detects that the channel is in use by performing the clear channel evaluation, or if it does not receive the acknowledgment response.

[0069] In the first aspect of the present invention, the slot selection unit 54 may select the transmission slot 56 according to a first rule when the count value N is less than a predetermined number of judgments, and may select the transmission slot 56 according to a second rule when the count value N is equal to or greater than the predetermined number of judgments.

[0070] A second aspect of the present invention is a communication method for a remote radio device 18 that transmits and receives signals to and from a base radio device 16 in a transmission / reception cycle, comprising: a transmission / reception processing step that executes a signal transmission process in each of a plurality of consecutive transmission / reception cycles until transmission to the base radio device 16 is successful; a counting step that counts the number of times the transmission process is executed; a transmission selection step that, if the count value N of the counting step is equal to or greater than a predetermined number, selects whether to execute the transmission process or wait in the next transmission / reception cycle according to a predetermined rule; and a transmission prohibition step that prohibits the transmission process if waiting is selected in the transmission selection step.

[0071] In a second aspect of the present invention, a slot selection step is provided for selecting one transmission slot 56 from a plurality of transmission slots 56 provided within each of the transmission and reception cycles and having different start timings for the transmission processing, and in the transmission and reception processing step, the transmission processing may be performed using the transmission slot 56 selected in the slot selection step.

[0072] In a second aspect of the present invention, in the transmission / reception processing step, the transmission processing may include a clear channel assessment, a signal transmission, and a reception of an acknowledgment response transmitted from the base radio device 16, and if the clear channel assessment detects that the channel is in use, or if the acknowledgment response is not received, it may be determined that the transmission has failed.

[0073] In a second aspect of the present invention, in the slot selection step, if the count value N is less than a predetermined number of determinations, the transmission slot 56 may be selected according to a first rule, and if the count value N is equal to or greater than the predetermined number of determinations, the transmission slot 56 may be selected according to a second rule. [Explanation of symbols]

[0074] 16...base radio device 18...remote radio device 44...Transmission and reception processing unit 46...Counting unit 48...Transmission selection unit 50...Transmission prohibition unit 54: Slot selection section 56: Transmission slot

Claims

1. A remote radio device that transmits and receives signals to and from a base radio device in a transmission and reception cycle, a transmission / reception processing unit that executes a transmission process of one packet of the signal in each of a plurality of successive transmission / reception periods until the transmission of one packet of the signal to the base radio device is successful; a counting unit that counts the number of times the transmission process for the one packet of signals has been executed; a transmission selection unit that selects whether to execute the transmission process of the one packet of signals or to wait for a next opportunity to execute the transmission process when the count value of the count unit is equal to or greater than a predetermined number of times, in accordance with a predetermined rule; a transmission prohibition unit that prohibits the transmission process of the one packet of signals that has failed to be transmitted when the transmission selection unit selects standby; Equipped with The remote radio device is configured such that, when the transmission prohibition unit prohibits the transmission of the one packet of signals that has failed to be transmitted, the transmission / reception processing unit waits without transmitting the signal to the base radio device.

2. 10. The remote wireless device of claim 1, a slot selection unit that selects one of a plurality of transmission slots that are provided in each of the transmission and reception periods and have different start timings for the transmission process of the one packet of signals; The remote radio device, wherein the transmission / reception processing unit executes the transmission processing of the one packet of signals using the transmission slot selected by the slot selection unit.

3. 3. A remote radio device according to claim 2, The remote radio device, wherein the transmission / reception processing unit performs the transmission processing of the one packet signal by performing a clear channel evaluation, transmitting the signal, and receiving an acknowledgment response transmitted from the base radio device, and determines that the transmission has failed if it detects that the channel is in use by performing the clear channel evaluation, or if it does not receive the acknowledgment response.

4. 3. A remote radio device according to claim 2, The slot selection unit selects the transmission slot in accordance with a first rule when the count value is less than a predetermined number of determinations, and selects the transmission slot in accordance with a second rule when the count value is equal to or greater than the predetermined number of determinations.

5. A communication method for a remote radio device that transmits and receives signals to and from a base radio device in a transmission and reception cycle, comprising: a transmission / reception processing step of executing a transmission process of one packet of the signal in each of a plurality of consecutive transmission / reception periods until the transmission of one packet of the signal to the base radio device is successful; a counting step of counting the number of times the transmission process for the one packet of signals has been executed; a transmission selection step of selecting whether to execute the transmission process of the one packet of signals or to wait for the next opportunity to execute the transmission process when the count value of the count step is equal to or greater than a predetermined number of times, in accordance with a predetermined rule; a transmission prohibition step of prohibiting the transmission process of the one packet of signals that has failed to be transmitted if waiting is selected in the transmission selection step; Equipped with A communication method for a remote radio device, in which, in the transmission / reception processing step, if the transmission processing of the one packet of signals that failed to be transmitted is prohibited in the transmission prohibition step, the remote radio device waits without transmitting to the base radio device.

6. 6. A method for communicating with a remote wireless device according to claim 5, comprising: a slot selection step of selecting one of a plurality of transmission slots provided in each of the transmission and reception periods and having different start timings for the transmission process of the one packet of signals, A communication method for a remote radio device, wherein in the transmission / reception processing step, the transmission processing for one packet of signals is performed using the transmission slot selected in the slot selection step.

7. 7. A method for communicating with a remote wireless device according to claim 6, comprising: In the transmission / reception processing step, the transmission processing of the one packet signal includes a clear channel evaluation, a signal transmission, and a reception of an acknowledgment response transmitted from the base radio device, and if the clear channel evaluation detects that the channel is in use or if the acknowledgment response is not received, the remote radio device determines that the transmission has failed.

8. 7. A method for communicating with a remote wireless device according to claim 6, comprising: In the slot selection step, if the count value is less than a predetermined number of determinations, the transmission slot is selected according to a first rule, and if the count value is equal to or greater than the predetermined number of determinations, the transmission slot is selected according to a second rule.

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