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

Abstract

To identify the position of a reference radio frame by a simple method.SOLUTION: A wireless communication system includes a wireless transmission device and a wireless receiving device that communicates with each other using frames, and the wireless receiving device detects a synchronization word included in a received frame, identifies a reference frame on the basis of the detected synchronization word, and controls transmission timing in synchronization with the identified frame.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a wireless communication system, and more particularly to a technique for realizing timing synchronization based on a base station signal in a mobile radio system in which timing cannot be generated between mobile stations.

Background Art

[0002] Among wireless communication systems, particularly the SCPC (Single Channel Per Carrier) method is suitable for performing communication by radio, and is easy to use for one-to-many communication, but is difficult to use for one-to-one communication. Although SCPC is mainly used for one-to-many communication, there are cases where one-to-one communication is additionally performed, for example, in position information or dynamic information. When mobile stations periodically transmit position information, in the SCPC method in which all mobile stations use the same frequency, it is necessary to shift the transmission timing between mobile stations. In order to synchronize the timing between mobile stations, it is necessary to use a common reference signal, and there is a method that uses an external system such as GPS that notifies time information from a base station as a reference.

[0003] As the background art in this technical field, there is the following prior art. In Patent Document 1 (Japanese Patent Application Laid-Open No. 2015-144408), a radio line control device and a plurality of base station radio devices operate at mutually synchronized timings, and when the radio line control device transmits a downlink transmission start instruction to the plurality of base station radio devices, as a downlink transmission start timing frame number attached to the start instruction, a frame number is set at an interval corresponding to the maximum value of the transmission time between the radio line control device and the plurality of base station radio devices with respect to the transmission timing of the downlink transmission start instruction. A wireless communication system is described.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As described above, in order to synchronize timings between mobile stations, it is necessary to use a common specification signal as a reference. For example, there is a method using an external system such as GPS that notifies time information from a base station as a specification. When notifying time information from a base station, since the time information is transmitted from the base station periodically, the amount of data that can be used for transmitting user data is reduced accordingly. Particularly in a narrowband system, the waste of data amount becomes a problem. Also, when using GPS as a specification, a GPS receiver is required on the mobile station side, resulting in increased costs.

[0006] An object of the present invention is to specify the position of a reference radio frame using a synchronization word.

Means for Solving the Problems

[0007] A typical example of the invention disclosed in the present application is as follows. That is, SCPC system consisting of multiple mobile stations A wireless communication system, Each of the mobile stations comprising a wireless transmission device and a wireless reception device that communicate using frames, The frames are grouped into superframes each containing a predetermined number of the frames. In the superframe, different synchronization words are assigned to the leading frame and the subsequent frames following the leading frame. The superframes are grouped into a superframe group each containing a predetermined number of the superframes. In the superframe group, different synchronization words are assigned to the frames in the leading superframe and the frames in the subsequent superframes following the leading superframe. A first synchronization word is assigned to the leading frame of the leading superframe, a second synchronization word is assigned to the subsequent frames of the leading superframe, and a third synchronization word is assigned to the leading frame of the subsequent superframe. the wireless reception device detects a synchronization word included in the received frame, When the synchronization word is the first synchronization word, the superframe group counter and the superframe counter are initialized. When the synchronization word is the second synchronization word, the second synchronization word detection flag is set to ON, and the superframe group counter and the superframe counter are initialized. When the synchronization word is the third synchronization word, it is determined whether the second synchronization word detection flag is ON. When the second synchronization word detection flag is ON, 1 is set to the superframe group counter, the second synchronization word detection flag is set to OFF, the superframe counter is initialized. When the second synchronization word detection flag is OFF, the superframe counter is initialized. the detected First identifies the frame by the synchronization word, and controls the transmission timing in synchronization with the identified , the leading of the leading superframe in the superframe group frame, which is characterized in that. , the leading of the leading superframe in the superframe group frame.

[0011] Also, in a wireless communication system according to an example of the present invention, the wireless reception device detects a head frame of a subsequent superframe in the superframe group by the third synchronization word (S3) of a frame after receiving the second synchronization word (S2).

[0012] Also, a wireless reception device according to an example of the present invention is SCPC system consisting of multiple mobile stations a wireless reception device that communicates with a wireless transmission device using frames,The frame is grouped into a superframe including a predetermined number of the frames. In the superframe, different synchronization words are assigned to the leading frame and the subsequent frames following the leading frame. The superframe is grouped into a superframe group including a predetermined number of the superframes. In the superframe group, different synchronization words are assigned to the frames in the leading superframe and the frames in the subsequent superframes following the leading superframe. A first synchronization word is assigned to the leading frame of the leading superframe, a second synchronization word is assigned to the subsequent frames of the leading superframe, and a third synchronization word is assigned to the leading frame of the subsequent superframe. The foregoing Other a wireless unit that receives a wireless signal from the wireless transmission device, a synchronization word detection unit that detects a synchronization word included in the wireless signal received by the wireless unit, and a control unit that controls the operation of the wireless reception device, wherein the control unit detects a synchronization word included in the received frame, When the synchronization word is the first synchronization word, the superframe group counter and the superframe counter are initialized. When the synchronization word is the second synchronization word, the second synchronization word detection flag is set to ON, and the superframe group counter and the superframe counter are initialized. When the synchronization word is the third synchronization word, it is determined whether the second synchronization word detection flag is ON. When the second synchronization word detection flag is ON, the superframe group counter is set to 1, the second synchronization word detection flag is set to OFF, the superframe counter is initialized. When the second synchronization word detection flag is OFF, the superframe counter is initialized. the detected First by the synchronization word , the leading of the leading superframe in the superframe group identifies the frame, and controls the transmission timing in synchronization with the identified the leading of the leading superframe in the superframe group frame.

[0014] Also, a wireless communication method according to an example of the present invention is In the SCPC system consisting of multiple mobile stations a wireless communication method of communicating between a wireless transmission device and a wireless reception device using a frame, wherein the frame is grouped into a superframe including a predetermined number of the frames, Within the superframe, different synchronization words are assigned to the first frame and the subsequent frames following the first frame. The superframe is grouped into a superframe group including a predetermined number of the superframes. Within the superframe group, different synchronization words are assigned to the frames within the first superframe and the frames within the subsequent superframes following the first superframe. A first synchronization word is assigned to the first frame of the first superframe, a second synchronization word is assigned to the subsequent frames of the first superframe, and a third synchronization word is assigned to the first frame of the subsequent superframe. in the wireless communication method, the wireless transmission device transmits a frame by assigning different synchronization words to a head frame and a subsequent frame following the head frame within the superframe, and the wireless reception device detects a synchronization word included in the received frame, When the synchronization word is the first synchronization word, the superframe group counter and the superframe counter are initialized. When the synchronization word is the second synchronization word, the second synchronization word detection flag is set to ON, and the superframe group counter and the superframe counter are initialized. When the synchronization word is the third synchronization word, it is determined whether the second synchronization word detection flag is ON. When the second synchronization word detection flag is ON, 1 is set to the superframe group counter, the second synchronization word detection flag is set to OFF, and the superframe counter is initialized. When the second synchronization word detection flag is OFF, the superframe counter is initialized. the detected First by the synchronization word , of the first superframe within the superframe group identifies the head frame, and controls the transmission timing in synchronization with the identified , of the first superframe within the superframe group head frame.

Advantages of the Invention

[0015] According to one aspect of the present invention, the position of a reference wireless frame can be specified by a simple method using a synchronization word. Problems, configurations, and effects other than those described above will be clarified by the description of the following embodiments.

Brief Description of the Drawings

[0016] [[FIG. 1]] It is a block diagram showing the configuration of a wireless communication device (mobile station) according to an embodiment of the present invention. [[FIG. 2]] It is a configuration diagram of a frame used by the wireless communication device according to an embodiment of the present invention. [[FIG. 3]] It is a diagram showing the relationship of the frame counter in an embodiment of the present invention. [[FIG. 4]] It is a flowchart of the counter initial synchronization process in an embodiment of the present invention. [[FIG. 5]] It is a block diagram showing the configuration of the wireless communication device (base station) in an embodiment of the present invention.

Mode for Carrying Out the Invention

[0017] FIG. 1 is a block diagram showing the configuration of the wireless communication device (mobile station) in an embodiment of the present invention.

[0018] The wireless communication device (mobile station) of this embodiment has a wireless unit 1, a synchronization word detection unit 2, a counter synchronization unit 3, a counter unit 4, a transmission data generation unit 5, a control unit 6, and a non-volatile memory area (non-volatile area in the figure) 7.

[0019] The wireless unit 1 is a wireless transceiver that transmits and receives wireless signals to and from other wireless communication devices (base stations). The synchronization word detection unit 2 detects the synchronization word included in the wireless signal received by the wireless unit 1. The counter synchronization unit 3 performs counter synchronization using the synchronization word detected by the synchronization word detection unit 2, and performs synchronization protection even when the detection of the synchronization word fails due to deterioration of the wireless signal or the like. The counter unit 4 counts a frame counter, a superframe counter, and a superframe group counter. Since the counter unit 4 continues to execute the count-up process until it can no longer detect the synchronization word continuously for a predetermined number of times, it can reduce the time required for resynchronization in an environment where the wireless signal is unstable. The transmission data generation unit 5 generates data to be transmitted in wireless communication. The control unit 6 controls the operation of the wireless communication device (mobile station). The non-volatile memory area 7 stores the operation timing (for example, transmission timing) used by the control unit 6.

[0020] FIG. 2 is a configuration diagram of the frame used by the wireless communication device in an embodiment of the present invention.

[0021] Between wireless communication devices (base stations and mobile stations), wireless frames are transmitted and received at a predetermined period (e.g., a period of 40 milliseconds). In addition to data, the wireless frame contains a synchronization word (e.g., a data array that does not appear in the data) for specifying frame timing.

[0022] Also, a structure of a superframe formed by bundling a plurality of frames is defined. With a superframe, one piece of data can be divided and transmitted over a plurality of frames, and data that does not fit into one frame can be bundled and transmitted in a superframe. A superframe is managed by a superframe group including a predetermined number (e.g., 80) of superframes. If one superframe is 720 milliseconds, the length of the superframe group is 57.6 seconds.

[0023] Here, it is necessary to distinguish between the first frame of the superframe and subsequent frames other than the first frame. For example, when a superframe is composed of 18 frames, all 18 frames can be received and the data can be decoded. However, if the first frame cannot be identified, the delimiter of the data aggregation cannot be correctly recognized and the data cannot be decoded. Therefore, the synchronization word is changed between the first frame and subsequent frames to identify the first frame. After detecting the synchronization word, the synchronization of the superframe can be established by receiving until the synchronization word of the next first frame is detected.

[0024] In this embodiment, not only is the synchronization word changed between the first frame and subsequent frames within the superframe, but as shown in FIG. 2, the synchronization word is also changed between the first frame and subsequent frames of the superframe group to form a superframe group in which a plurality of superframes are bundled.

[0025] For example, as shown in FIG. 2, four types of synchronization words, S1 to S4, are prepared and arranged in each superframe according to a predetermined rule. The synchronization word S1 is arranged in the first frame within the first superframe of the superframe group, and the synchronization word S2 is arranged in the subsequent frame within the first superframe of the superframe group. Also, the synchronization word S3 is arranged in the first frame within the subsequent superframe of the superframe group, and the synchronization word S4 is arranged in the subsequent frame within the subsequent superframe of the superframe group. That is, the synchronization words S1 and S2 are assigned to the first superframe within the superframe group, and the synchronization words S3 and S4 are assigned to the subsequent superframes other than the first superframe within the superframe group. Also, the synchronization words S1 and S3 are assigned to the first frame within the superframe, and the synchronization words S2 and S4 are assigned to the subsequent frames within the superframe.

[0026] Note that in this embodiment, the same synchronization word S2 is arranged in the subsequent frames within the first superframe of the superframe group, but the synchronization words of the subsequent frames may be different. For example, the synchronization word of the first subsequent frame may be S2-1, the synchronization word of the next subsequent frame may be S2-2, and the synchronization word of the nth subsequent frame may be S2-n. Similarly, the same synchronization word S4 is arranged in the subsequent frames within the subsequent superframe of the superframe group, but the synchronization words of the subsequent frames may be different. For example, the synchronization word of the first subsequent frame may be S4-1, the synchronization word of the next subsequent frame may be S4-2, and the synchronization word of the nth subsequent frame may be S4-n.

[0027] Then, as shown in FIG. 3, a superframe group counter which is an integration counter for counting the number of superframes from the first superframe of the superframe group, and a superframe counter which is an integration counter for counting the number of frames within the superframe from the first frame of the superframe are provided. By combining the superframe group counter and the superframe counter, a unique frame counter within the superframe group can be calculated, the start of the superframe group can be recognized, and the position of the received frame within the superframe group can be specified. Thereby, each mobile station can synchronize timing with other mobile stations connected to the same base station. Also, a frame counter that counts in frame units is provided.

[0028] Next, with reference to FIGS. 1 and 4, a procedure for processing a radio signal received by a mobile station from a base station will be described.

[0029] The synchronization word detection unit 2 detects the synchronization word included in the radio signal received by the radio unit 1 and specifies the frame timing of the received radio signal.

[0030] Next, the counter synchronization unit 3 performs initial synchronization of counter synchronization of the superframe and the superframe group according to the procedure of FIG. 4 from the synchronization word detected by the synchronization word detection unit 2.

[0031] First, it is determined whether the synchronization word is S1 (step 11). The synchronization word S1 is assigned to the first frame of the first superframe within the superframe group. Therefore, when the synchronization word is S1, since this frame is the first frame of the first superframe within the superframe group, the superframe group counter and the superframe counter are initialized (steps 14 and 15).

[0032] If the synchronization word is not S1, it is determined whether the synchronization word is S2 (step 12). The synchronization word S2 is assigned to the frame following the first superframe within the superframe group. Therefore, if the synchronization word is S2, since this frame is the frame following the first superframe within the superframe group, the S2 detection flag is set to ON (step 16). With the S2 detection flag, the superframe following the first superframe can be detected. Then, the superframe group counter is initialized (step 17), and the superframe counter is initialized (step 15). Thereby, even if the synchronization word S1 is missed, the initial synchronization of counter synchronization can be performed.

[0033] If the synchronization word is not S2, it is determined whether the synchronization word is S3 (step 13). The synchronization word S3 is assigned to the first frame of the subsequent superframe within the superframe group. Therefore, if the synchronization word is S3, this frame is the first frame of the subsequent superframe within the superframe group. Therefore, it is determined whether the S2 detection flag is ON (step 18). Here, if the S2 detection flag is ON (Y in step 18), since the previous superframe is the first in the superframe group, 1 is set to the superframe group counter (step 19), the S2 detection flag is set to OFF (step 20), and the superframe counter is initialized (step 15). That is, as shown in FIG. 3, the superframe counter is initialized to 0 at the detection timing of the synchronization word S3, and the superframe group counter is set to 1 at the detection timing of the first synchronization word S3 after the synchronization word S2 is detected (step 19).

[0034] On the other hand, if the S2 detection flag is OFF (N in step 18), since the synchronization words S1 and S2 have not been detected, the superframe counter is initialized (step 15), and the counter initial synchronization process is terminated.

[0035] Also, when the synchronization word is not S3 (N in step 13), since it is the synchronization word S4, the counter initial synchronization process is terminated as it is without initializing the superframe group counter and the superframe counter.

[0036] By the above processing, even if the synchronization word S1 cannot be received in the counter initial synchronization process, the superframe group counter can be set by receiving the synchronization word S2 consecutive to the synchronization word S1, and the probability of synchronizing the counter value can be improved.

[0037] After the counter initial synchronization process is completed by the counter synchronization unit 3, the counter unit 4 executes the count-up process of the frame counter, the superframe counter, and the superframe group counter at the period shown in FIG. 3.

[0038] The control unit 6 calculates the transmission timing from the obtained various counter values and generates transmission data. Here, the control unit 6 specifies the reference frame by the synchronization word detected by the synchronization word detection unit 2, detects the specified reference frame, and determines the transmission timing so as not to collide between mobile stations in synchronization with the detected frame. For this reason, the determined transmission timing is set in the non-volatile storage area 7 in advance. Also, the transmission timing may be set from a base station or the like to the mobile station.

[0039] The radio unit 1 sends a radio signal to the base station with the generated transmission data at the calculated transmission timing.

[0040] At this time, the control unit 6 may calculate the transmission timing by the superframe group counter.

[0041] Also, the transmission timing may be calculated using the frame period counter calculated from the superframe group counter and the superframe counter. Since the number of frames in the superframe is a predetermined number, it can be calculated by the following formula. In this case, the transmission timing can be specified in detail, and the data transmission efficiency can be increased. Frame period counter number = Superframe group counter × Number of superframes + Superframe counter

[0042] FIG. 5 is a block diagram showing the configuration of a wireless communication device (base station) according to an embodiment of the present invention.

[0043] The wireless communication device (base station) of this embodiment includes a radio section 31, a synchronization word generation section 32, a transmission data generation section 33, and a control section 34.

[0044] The radio section 31 is a radio transceiver that transmits and receives radio signals to and from other wireless communication devices (mobile stations). The synchronization word generation section 32 generates a synchronization word included in a radio signal received by the wireless communication device (mobile station) as described above with reference to FIG. 2 and the like. The transmission data generation section 33 generates data to be transmitted in wireless communication. The control section 34 controls the operation of the wireless communication device (base station). For example, the control section 34 includes, for example, a GPS receiver or a high-precision frequency oscillator, controls which of the synchronization words S1 to S4 the synchronization word generation section 32 generates, and further controls the transmission timing of the radio signal by the radio section 31.

[0045] So far, the embodiments have been described with the wireless communication device (base station) as the transmission side and the wireless communication device (mobile station) as the reception side, but the transmission side and the reception side may be other combinations. For example, the wireless communication device (mobile station) may be the transmission side and the wireless communication device (base station) may be the reception side, or the wireless communication device (mobile station) may be the transmission side and another wireless communication device (mobile station) may be the reception side.

[0046] As described above, according to the embodiments of the present invention, the position of a reference radio frame can be specified by a simple method using a plurality of types of synchronization words without providing a special device. As a result, the number of frames from the reference radio frame can be made consistent among mobile stations connected to the same base station, the timing can be synchronized among the mobile stations, and data can be transmitted without interfering with other mobile stations. Further, since synchronization words necessary for synchronization of radio frames are used, it is not necessary to insert special data for frame synchronization, and the position of the reference radio frame can be specified without affecting the amount of data that can be transferred.

[0047] Note that the present invention is not limited to the above-described embodiments, and includes various modifications and equivalent configurations within the scope of the appended claims. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and the present invention is not necessarily limited to those having all the configurations described. Also, a part of the configuration of one embodiment may be replaced with the configuration of another embodiment. Further, the configuration of another embodiment may be added to the configuration of one embodiment. Also, for a part of the configuration of each embodiment, addition, deletion, or replacement with other configurations may be performed.

[0048] In addition, each of the above-described configurations, functions, processing units, processing means, etc. may be realized in hardware by designing a part or all of them, for example, by using an integrated circuit, or may be realized in software by a processor interpreting and executing a program that realizes each function.

[0049] Information such as programs, tables, and files that realize each function can be stored in a storage device such as a memory, a hard disk, an SSD (Solid State Drive), or a recording medium such as an IC card, an SD card, or a DVD.

[0050] Also, control lines and information lines show those considered necessary for explanation, and do not necessarily show all the control lines and information lines necessary for implementation. In reality, it may be considered that almost all configurations are interconnected.

Description of Reference Numerals

[0051] 1. 31 Wireless Unit 2. Synchronization Word Detection Unit 3. Counter Synchronization Unit 4. Counter Unit 5. 33 Transmission Data Generation Unit 6. 34 Control Unit 7. Non-Volatile Memory Area 32. Synchronization Word Generation Unit

Claims

1. An SCPC-based wireless communication system comprising a plurality of mobile stations, wherein each of the mobile stations includes a wireless transmission device and a wireless reception device that communicate using frames, the frames are grouped into superframes each including a predetermined number of the frames, within the superframe, different synchronization words are assigned to the leading frame and the subsequent frames following the leading frame, the superframes are grouped into a superframe group including a predetermined number of the superframes, within the superframe group, different synchronization words are assigned to the frames in the leading superframe and the frames in the subsequent superframes following the leading superframe, a first synchronization word is assigned to the leading frame of the leading superframe, a second synchronization word is assigned to the subsequent frames of the leading superframe, a third synchronization word is assigned to the leading frame of the subsequent superframe, the wireless reception device detects the synchronization word included in the received frame, when the synchronization word is the first synchronization word, initializes the superframe group counter and the superframe counter, when the synchronization word is the second synchronization word, sets the second synchronization word detection flag to ON, and initializes the superframe group counter and the superframe counter, when the synchronization word is the third synchronization word, determines whether the second synchronization word detection flag is ON, when the second synchronization word detection flag is ON, sets 1 to the superframe group counter, sets the second synchronization word detection flag to OFF, and initializes the superframe counter, when the second synchronization word detection flag is OFF, initializes the superframe counter, identifies the leading frame of the leading superframe within the superframe group based on the detected first synchronization word, and controls the transmission timing in synchronization with the leading frame of the leading superframe within the identified superframe group. A wireless communication system characterized by the above.

2. The wireless communication system according to claim 1, The wireless communication system is characterized in that the wireless receiving device detects a leading frame of a subsequent superframe in the superframe group by means of the third synchronization word of a frame after receiving the second synchronization word. **Claim 3**: A wireless receiving device that communicates with a wireless transmitting device of an SCPC system composed of a plurality of mobile stations using frames, wherein the frames are grouped into superframes each including a predetermined number of the frames, in the superframe, different synchronization words are assigned to a leading frame and a subsequent frame following the leading frame, the superframes are grouped into a superframe group including a predetermined number of the superframes, in the superframe group, different synchronization words are assigned to frames in a leading superframe and frames in a subsequent superframe following the leading superframe, a first synchronization word is assigned to the leading frame of the leading superframe, a second synchronization word is assigned to a subsequent frame of the leading superframe, a third synchronization word is assigned to the leading frame of the subsequent superframe, a wireless section that receives a wireless signal from the other wireless transmitting device, a synchronization word detection section that detects a synchronization word included in the wireless signal received by the wireless section, and a control section that controls the operation of the wireless receiving device, wherein the control section detects a synchronization word included in a received frame, when the synchronization word is the first synchronization word, initializes a superframe group counter and a superframe counter, when the synchronization word is the second synchronization word, sets a second synchronization word detection flag to ON, initializes a superframe group counter and a superframe counter, when the synchronization word is the third synchronization word, determines whether the second synchronization word detection flag is ON, when the second synchronization word detection flag is ON, sets 1 to the superframe group counter, sets the second synchronization word detection flag to OFF, and initializes the superframe counter, when the second synchronization word detection flag is OFF, initializes the superframe counter, identifies the leading frame of the leading superframe in the superframe group by means of the detected first synchronization word, A wireless receiving apparatus characterized by controlling transmission timing in synchronization with a leading frame of a leading superframe within the specified superframe group. **Claim 4**: A wireless communication method for communicating using frames between a wireless transmitting apparatus and a wireless receiving apparatus in an SCPC system including a plurality of mobile stations, wherein the frames are grouped into superframes each including a predetermined number of the frames, wherein different synchronization words are assigned to a leading frame and a subsequent frame following the leading frame within the superframe, wherein the superframes are grouped into a superframe group each including a predetermined number of the superframes, wherein different synchronization words are assigned to frames within a leading superframe and frames within a subsequent superframe following the leading superframe within the superframe group, wherein a first synchronization word is assigned to a leading frame of the leading superframe, wherein a second synchronization word is assigned to a subsequent frame of the leading superframe, wherein a third synchronization word is assigned to a leading frame of the subsequent superframe, wherein the wireless communication method includes: the wireless transmitting apparatus transmitting frames by assigning different synchronization words to a leading frame and a subsequent frame following the leading frame within the superframe, the wireless receiving apparatus detecting a synchronization word included in a received frame, initializing a superframe group counter and a superframe counter when the synchronization word is the first synchronization word, setting a second synchronization word detection flag to ON, initializing a superframe group counter and a superframe counter when the synchronization word is the second synchronization word, determining whether the second synchronization word detection flag is ON when the synchronization word is the third synchronization word, setting 1 to the superframe group counter, setting the second synchronization word detection flag to OFF, and initializing the superframe counter when the second synchronization word detection flag is ON, initializing the superframe counter when the second synchronization word detection flag is OFF, identifying a leading frame of a leading superframe within the superframe group based on the detected first synchronization word. A wireless communication method characterized by controlling a transmission timing in synchronization with a head frame of a head superframe within the specified superframe group.

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