JP5994988B2 - TDMA communication system for flying object, flying object, and TDMA communication method for flying object - Google Patents

Description

  The present invention relates to a TDMA (Time Division Multiple Access) communication system, and more particularly to a wide area TDMA communication system for flying objects.

  Technologies related to the TDMA communication system are described in Patent Documents 1 and 2, for example.

  Patent Document 1 describes a TDMA communication technique used between flying objects. In the technique described in Patent Document 1, the reference burst slots of all mobile stations are allocated on the superframe. By assigning a plurality of reference burst slots to a superframe in this way, any station can transmit a reference burst in a designated reference burst slot, and each station can broadcast synchronization establishment information in the reference burst slot. Yes. That is, by allocating the reference burst slots for all stations on the superframe, it is possible to exchange synchronization establishment information between mobile stations, and even if the main station for synchronization leaves, either The mobile station becomes the main station, and superframe synchronization between the mobile stations is maintained.

  Patent Document 2 describes a technique for synchronizing the phases of output frames between slave stations in a TDMA communication system having a master station (main station) and a plurality of slave stations (subordinate stations). In the technique described in Patent Document 2, a super frame composed of a plurality of standard frames is created in a master station. The delay time is obtained by an alignment circuit group (loop circuit) provided between the master station 10 and the slave station 20, and the superframe is delayed by the delay time in the slave station. Thereby, all the phases of the super frame in each slave station can be matched.

JP 2000-49738 A JP 10-41874 A

  By the way, in the technique described in Patent Document 1, it is necessary to allocate the reference burst slots on the superframe by the number of mobile stations subordinate to the network. Further, in this technique, since the timing of the superframe is defined in accordance with the mobile station that is the main station, no consideration is given to communication delay, synchronization shift, and the like between mobile stations different from the main station. This leads to the occurrence of mobile stations that must leave the main stations when switching the main stations.

  On the other hand, although the technique described in Patent Document 2 is based on the master station (main station) and can perform output frame synchronization in a plurality of slave stations, the slave station is limited to a fixed station. Further, no consideration is given to instantaneous radio wave changes that change from moment to moment due to fading, fluctuations, and the like.

  In the above technique, a high-speed and stable wireless environment cannot be provided for a flying object, such as communication between a communication system having a plurality of ground base stations and the flying object.

  An object of the present invention is to provide a TDMA communication system, a flying object, and a TDMA communication method for a flying object that can provide a high-speed and stable wireless environment for the flying object.

The TDMA communication system according to the present invention divides a predetermined number of time slots into a plurality of slot groups, distributes the time slots of the slot groups so as to be adjacent to different groups of time slots, and sets each slot group at the beginning of a frame. Using a TDMA frame format in which synchronization time slots are arranged side by side, a plurality of base stations that construct a coverage area, a central station that manages the plurality of base stations and communicates with the flying object, and one or more flying objects The system synchronization information is transmitted from the plurality of base stations to all the synchronization time slots of the slot group, and the flying object sets the use frequency channel of the TDMA radio for each slot group, Acquires system synchronization information included in each synchronization time slot and switches the base station used for communication with the central station At the time of a handover, a plurality of system synchronization information transmitted from the respective base stations that construct the belonging coverage area and the movement destination coverage area respectively included in the plurality of synchronization time slots The handover is completed through a process of detecting using and dividing a plurality of slot groups and enabling communication with the central station via both base stations .
A flying body equipped with a TDMA radio according to the present invention divides a predetermined number of time slots into a plurality of slot groups and performs synchronization processing using a time in a TDMA format frame in which a synchronization time slot is provided for each slot group, All of the plurality of synchronization time slots included in the TDMA format frame are detected using the frequency channels used in the coverage area, and the system synchronization information for each slot group is obtained from each synchronization time slot. Acquire each and specify one or more base stations to be wirelessly connected and information on the superframe itself and specific information on the remaining time slots in the same superframe based on the system synchronization information for each slot group And switching the base station used for communication when communicating with the central station that supervises a plurality of base stations. At the time of handover, a plurality of synchronization time slots are obtained from the system synchronization information transmitted from the respective base stations that construct the belonging coverage area and the movement destination coverage area included in each of the plurality of synchronization time slots. The handover is completed through a process of detecting using and dividing a plurality of slot groups and enabling communication with the central station via both base stations.
In the TDMA communication method for a flying object according to the present invention, a predetermined number of time slots are divided into a plurality of slot groups, and the time slots of the slot groups are distributed and arranged so as to be adjacent to different time slots. First, the TDMA frame format in which the synchronization time slots of each slot group are arranged side by side is used by a plurality of base stations and flying bodies that construct a coverage area, and the central station that supervises the plurality of base stations and the flying bodies When communicating, the plurality of base stations transmit system synchronization information to all the synchronization time slots of the slot group, and the flying object sets the frequency channel of the TDMA radio for each slot group. The system synchronization information included in each synchronization time slot is acquired and the base station used for communication with the central station is switched. At the time of handover, a plurality of synchronization time slots are obtained from the system synchronization information transmitted from the respective base stations that construct the belonging coverage area and the movement destination coverage area included in each of the plurality of synchronization time slots. The handover is completed through a process of detecting using and dividing a plurality of slot groups and enabling communication with the central station via both base stations.

  ADVANTAGE OF THE INVENTION According to this invention, the TDMA communication system which can provide a high-speed and stable radio | wireless environment with respect to a flying body can be provided.

It is explanatory drawing which shows the structure of the TDMA radio system in embodiment. It is explanatory drawing which illustrates the structure of a super frame. It is explanatory drawing which shows the receiving environment in the flying body with respect to a super frame. It is explanatory drawing which shows the receiving environment from the several base station in the flying body with respect to a super frame. 4 is an explanatory diagram illustrating a reception environment in a covered area P. FIG. It is explanatory drawing which illustrates the receiving environment in the coverage area Q. 3 is an explanatory diagram illustrating a reception environment in a covered area R. FIG. It is explanatory drawing which shows the state which belongs only to 1 coverage before the handover process start. It is explanatory drawing which shows the transition state 1 which belongs to 2 coverage at the time of a handover process. It is explanatory drawing which shows the transition state 2 which belongs to 2 coverage at the time of a handover process. It is explanatory drawing which shows the state which belongs only to 1 coverage after a handover process.

  An embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is an explanatory diagram illustrating a configuration of a TDMA radio system according to the embodiment. In the explanatory diagram, requirements of some communication systems are described.
On the ground, a plurality of base stations (21, 22, 23) connected to the central station 10 and the central station 10 through communication lines are installed. A flying object 100 serving as a communication partner of the central station 10 is flying above the base station group.

  Each of the base station groups (21, 22, 23) operates as a subordinate to the central station 10, and transmits a radio communication wave using a predetermined use frequency channel to form a covered area in the atmosphere. The flying object 100 located in the covered area can perform data communication or data link using the frequency channel used by each base station (21, 22, 23). It is desirable to operate by providing overlapping areas in the coverage areas constructed by individual base stations. Further, the coverage area may be overlapped by two or more base stations. In the figure, there is an overlap in the coverage areas constructed by the X base station 21 and the Y base station 22, respectively, and there is an overlap in the coverage areas constructed by the Y base station 22 and the Z base station 23, respectively. Note that the present invention is not limited to the configuration shown in the figure, and three or more base stations may be provided to increase the overlap of the coverage areas so that the used frequencies do not overlap.

  The TDMA method is used as the communication method. In the present embodiment, the synchronization information defines information unique to the superframe and individual time slots at the central office 10. Also, the time slots included in the superframe are divided into a plurality of slot groups, and at least one synchronization information is assigned to each slot group so that each slot group is adjacent to a different group of time slots. Are distributed (described in detail in FIG. 2).

  The flying object 100 is equipped with a TDMA radio in addition to the function as a flying object. Moreover, if necessary, a device used for information processing such as a data link device is mounted. The flying object 100 uses the time slot allocated from the central office 10 to deliver desired information. The TDMA radio device that the flying object 100 has has a function of switching the used frequency channel for each time slot. Moreover, the process which adjusts the data length (time) received by each slot as needed can be performed. In addition, in the same superframe, allocation of frequency channels to be used is handled separately for each slot group. The allocation of the frequency channels to be used may be determined for each coverage area in advance, or the entire system or the flying object- What is necessary is just to determine between base stations.

FIG. 2 is an explanatory diagram illustrating the structure of a superframe.
The superframe employed in the present embodiment consists of a total of 48 slots starting from the A0 slot and ending with the C15 slot, and these slots are composed of a plurality of slot groups (group A, group B, group C). In the figure, each slot group is divided into 16 groups, group A (A0 to A15: set A), group B (B0 to B15: set B), and group C (C0 to C15: set C). The slots are distributed so as to be adjacent to the slots.

  The flying object 100 communicates with one base station having the same frequency channel by using the same frequency channel for all time slots belonging to each group (each set) in the same superframe. On the other hand, when different frequency channels are used for the three slot groups, the base station group (21, 22, 23) is switched to the frequency channel used by the base station group (21, 22, 23) for each slot. Can communicate with.

  In the present embodiment, the time slot (A0, B0, C0 slot) located at the head of each group of superframes is set as a system synchronization time slot. Information for system synchronization is transmitted from each base station to the atmosphere in three synchronization time slots A0, B0, and C0 (broadcast transmission).

  At this time, in the flying object 100, the setting of the TDMA radio is set for each slot group with the frequency channel used in the coverage area to which it belongs or belongs, and the A0, B0, C0 slots that are the synchronization time slots Is acquired, and the data position in each time slot in the TDMA format frame is specified using the system synchronization information. The flying object 100 establishes communication with the central station 10 via the base station based on the detected data position.

  The slots from A0 to C15 are equal T1 time slots. However, it is not always necessary that the time slots have the same length. For example, the synchronization slot may be shortened or the data communication slot may be biased. In addition, it is desirable to arbitrarily provide a Tgi guard interval between each time slot (see the lower part of FIG. 2).

Here, problems in flying object communication will be described with reference to FIGS.
FIG. 3 is an explanatory diagram illustrating a reception environment of a flying object for a super frame.
If the X base station 21 sends a signal (radio wave) toward the flying object 100 located in the coverage area P with the frequency channel Fx, the flying object 100 causes a delay of ΔTa to the transmitted signal. The time difference occurs between the super frame and the actually received signal.

  This is because the actually received signal is affected by many delays while the flying object 100 (or the timing thereof) coincides with the timing of the super frame. For example, the base station group (21, 22, 23), the central station 10 and the flying object 100 are generated by the central station 10 when the time information using GPS (Global Positioning System) matches the superframe timing. When the received information is transmitted from a predetermined base station, the reception timing of the signal affected by the transmission time to the base station, the propagation time in the air, the processing time of each place, fading, etc. A time lag occurs after the frame (individual slot) timing. Even if the information generated by the central station 10 is buffered at a predetermined base station and transmitted after timing adjustment, there will still be a shift due to other factors.

FIG. 4 is an explanatory diagram showing a reception environment from a plurality of base stations in a flying object for a super frame.
FIG. 4 explicitly shows the reception timing when the flying object 100 is located in the coverage area of the base station 21 and can communicate with the other base stations 22 and 23. Assuming that the central station 10 communicates with the flying object 100 using the slots of the X base station 21 to the A group, the Y base station 22 to the B group, and the Z base station 23 to the C group, the flying object 100. Then, delays of ΔTa, ΔTb, and ΔTc occur in each slot group. This delay changes from moment to moment depending on the position of the flying object 100 and the base stations (21, 22, 23) and the propagation environment.

  As shown in FIGS. 3 and 4, when signals are received from a plurality of base stations, different delays occur for each group. Due to the presence of the delay and individual changes, the allowable transmission time of the slot (the width of T2 in FIG. 4) is limited. Therefore, the transmission / reception device adjusts the data length while taking into consideration the allowable transmission time of the slot (= the allowable reception time of the flying object).

  Next, the reception environment of the system synchronization time slot in the flying object 100 will be described.

  The time slot (A0, B0, C0 slot) located at the head of each group of superframes is used as a system synchronization time slot. In all system synchronization time slots, NTR (Network Time Reference) information is inserted by each base station as system synchronization information and transmitted from the frequency channel used in each base station.

  NTR (Network Time Reference) information is information such as frequency information from the A0, B0, and C0 slots to the A15, B15, and C15 slots in the TDMA format superframe, the current superframe number, and the slot number for storing specific data. .

  FIG. 5 is an explanatory diagram illustrating a reception environment in the covered area P. Here, the covered area P is an area where it is desirable to mainly communicate with the X base station 21. FIG. 5 shows a reception environment as to how the time slot for system synchronization transmitted from all the other base stations (21, 22, 23) reaches the flying object 100 in the coverage area P.

  As shown in the figure, the difference in delay from the same station for each slot can be seen in very few cases. On the other hand, when the base station is different, a difference occurs in the delay amount.

FIG. 6 is an explanatory diagram illustrating the reception environment in the coverage area Q.
FIG. 7 is an explanatory diagram illustrating a reception environment in the coverage area R.
Also in the coverage areas Q and R, like the coverage area P, the difference in delay from the same station is very small for each slot, and a difference in delay amount occurs between signals from different base stations. Further, the delay amount changes for each covered area from the positional relationship between the flying object 100 and the base station that transmits the NTR information.

In the normal TDMA communication system, even if the radio wave reception sensitivity is an allowable amount, a signal that protrudes from the time slot cannot be used. On the other hand, increasing the guard interval time is directly linked to shortening the time interval that can be used for transmission / reception of communication data, thereby reducing the identification of communication data (symbols) and reducing the amount of communication data constantly. Connected. That is, the provision of a high-speed and stable wireless environment is affected.
In the actual environment, the positional relationship between the flying object and multiple base stations varies, and the reception status of the flying object depends on the surrounding environment as well as the attenuation due to distance. It is difficult to predict a base station with good sensitivity in advance.

Therefore, from the base stations (21, 22, 23) connected to the central station 10, the first three slots (A0, B0, C0) in the superframe are used as synchronization time slots, and frequency channels (Fx, Fy) are respectively used. , Fz), and NTR information including the synchronization timing is put in all of A0, B0, and C0, and broadcast transmission is performed. In other words, similar NTR information is transmitted on the frequency channel of the base station at the timings of the A0, B0, and C0 slots.
In this way, the flying object 100 that is wirelessly connected to the base station sets the frequency channel used by the TDMA radio to the frequency channel (Fx, Fy, or Fz) used in the covered coverage area. NTR information contained in the A0, B0, and C0 slots can be acquired. That is, the flying object 100 acquires the NTR information contained in the A0, B0, and C0 slots, respectively, and from this NTR information to the A15, B15, and C15 slots after the A0, B0, and C0 slots in the TDMA format superframe. Obtain frequency information, current superframe number, time slot number for data transmission or reception, storage slot number for specific data, data head position information, data length as required, etc. Can be obtained.

  Next, the flying object 100 of this embodiment is demonstrated.

The flying object 100 has a GPS device and can acquire accurate time information from a GPS satellite. A highly accurate internal clock may be used.
Further, the flying object 100 can acquire the position information of the own aircraft.
The frame synchronization of the flying object 100 with respect to the base station and the central station 10 uses time information from GPS. That is, it synchronizes with time.

  After making the superframe coincide with the GPS time, the flying object 100 acquires the NTR information included in the A0 slot using the TDMA radio, and performs system synchronization of the group A based on the NTR information. Similarly, the B and C groups acquire NTR information contained in the B0 and C0 slots and perform system synchronization. By the system synchronization, information can be exchanged at high speed and stably using each slot.

  In other words, in the state shown in FIG. 4, the flying object synchronizes with the superframe using time, and uses the system synchronization information included in each synchronization time slot. The data acquisition timing is identified, the frequency channel for each slot group is switched, and communication data is read at that timing.

Next, an example of operation as a TDMA communication system will be described.
The central station 10 assigns a transmission / reception time slot for each flying object 100. The transmission time slot is assigned to the same flying object 100 by using a time slot of each group for each base station and transmitting using different frequency channels within one superframe. If handover between coverage areas is not considered, communication using all slots from A1 slot to C15 slot for data transmission is possible if the A0, B0, and C0 slots are synchronized.

In addition, the central station 10 determines a frequency channel to be used for each slot group of the flying object 100. Further, the transmission data length for each slot group is determined.
The flying object 100 scans the slots A0, B0, C0 of the frequency channel designated by the central station 10 in advance or in the previous superframe every superframe to achieve system synchronization with each slot group.
At this time, in the communication performed using each group in one superframe, the flying object 100 uses the frequency channels (Fx, Fy, Fz) used by the base stations (21, 22, 23) for the A0, B0, and C0 slots, respectively. ) To scan (change the reception frequency channel in the order of Fx, Fy, Fz) and acquire NTR information. After acquiring NTR information, frequency information of subsequent time slots from the NTR information, current superframe number, time slot number for data transmission or reception, storage slot number of specific data, data head position information, if necessary The used data length, etc. are acquired, and data is acquired using some of the A15, B15, and C15 slots from the A1, B1, and C1 slots. This is because in the flying object 100, it is possible to satisfactorily communicate with any slot using any frequency channel. That is, the synchronization timing of each slot of the super frame is acquired at the head portion of the super frame. In this way, each flying object 100 exchanges desired data using the slots allocated in each group based on the information acquired from the central station 10.

  As described above, by using this TDMA communication system, a high-speed and stable wireless environment can be provided for the flying object. This technique is suitable for, for example, a data link or transmission / reception of a large volume of data. However, in order to receive A, B, C, and three groups, the communication time in each time slot is adjusted to end within each time slot in consideration of the guard time for the communication delay time.

  Next, a mechanism for performing handover in order to obtain high-speed and stable wireless communication with a flying object in the TDMA communication system of the above embodiment will be described. The flying object 100 is requested to perform handover when moving from a coverage area constructed by a predetermined base station to a coverage area constructed by another base station while maintaining the data link. In the above communication method, by performing handover as described below, it is possible to change the base station that performs communication while maintaining the data link at high speed and in a stable state.

  In the following description, the case where the flying object 100 moves from the coverage area Q of the Y base station 22 to the coverage area P of the X base station 21 will be described. At this time, the frequency channel Fy is used in the coverage area Q, and the frequency channel Fx is used in the coverage area P.

  8 to 11 are explanatory diagrams showing the operation of each station at the time of handover. FIG. 8 shows a case where the flying object 100 belongs to only one coverage area before the handover process is started (normal state). Note that description of the Z base station 23 not involved in the handover process is omitted.

  The X base station 21 and the Y base station 22 continuously broadcast NTR information at the timings of the A0, B0, and C0 slots using the respective frequency channels Fx and Fy that are used.

  The flying object 100 identifies the coverage area Q based on its own position information and / or instruction information from the central station 10 and uses the frequency channel used by the base station 22 at the timing of each of the A0, B0, and C0 slots. It waits for Fy and receives it, and acquires the system synchronization timing of each of the slots A, B, and C.

In this way, by using the timings of the slots A0, B0, and C0 for the reception timings of all slots of the A group, the B group, and the C group, respectively, all the slots of the A group, the B group, and the C group (superframes). All of the above) enables transmission / reception of data to / from the Y base station.
In other words, the flying object 100 synchronizes with the wireless system in the frequency channel used in the coverage area that belongs, and realizes data communication using the synchronized timing of each slot, and in the A group, the B group, and the C group. By confirming the reception information by accumulating the transmission / reception information of three times, more robust information transmission becomes possible. The base station can also be stacked in the same way.

  Information regarding the coverage area of the destination may be stored in advance or may be acquired from the central office 10. For example, the switching timing (coordinates), the switching destination frequency, and the like may be notified from the central station 10 in accordance with the moving target of the flying object.

FIG. 9 shows a case where the flying object 100 moves and belongs to the two coverage areas at the time of the handover process (a state where the flying object 100 is close to the base station before movement).
As in the example of FIG. 8, the X base station 21 and the Y base station 22 broadcast NTR information at the timings of the A0, B0, and C0 slots using Fx and Fy that are the respective use frequency channels.

  The flying object 100 starts the switching process based on an instruction from itself or the central station 10 and receives it using the frequency channel Fy used by the base station 22 at the timing of the time slots A0 and B0. The system synchronization timing of the group B is acquired and received using the frequency channel Fx used by the base station 21 at the timing of the time slot C0 to acquire the system synchronization timing of the slot C group. In this operation, in the flying object 100, one slot group is synchronized with the frequency channel used in the coverage area of the moving destination, and the frequency channel for transmitting data is changed to Fx using the synchronized slot group. It is. In other words, in the boundary area, it is impossible to estimate the position of the flying object 100 between the base station 21 and the base station 22 due to various external environmental factors, so that it can be received from the base station 21. This is an attempt to measure the timing at which reception is possible by using the frequency channel Fx used by the base station 21 at the timing.

  FIG. 10 shows a case where the mobile station belongs to two coverage areas at the time of the handover process (a state where the mobile station is close to the base station after movement).

  As in the example of FIG. 8, the X base station 21 and the Y base station 22 broadcast NTR information at the timings of the A0, B0, and C0 slots using Fx and Fy that are the respective use frequency channels.

  The flying object 100 starts the switching process based on an instruction from itself or the central station 10 and receives using the frequency channel Fy used by the base station 22 at the timing of the time slot A0, and synchronizes the system of the slot A group. The timing is acquired, and the frequency channel Fx used by the base station 21 is awaited and received at the timing of the time slots B0 and C0, and the system synchronization timing of the slot B group C group is acquired.

  In this operation, in the flying object 100, by assigning two slots (groups B and C) to the frequency Fx used in the coverage P in the moving direction in a specific super frame, the reception level is low and unstable. This is an operation of receiving communication with the base station 21 that is expected to be received twice and stacking it up to obtain strong information.

  As described above, by dividing the reception timing of all slots of the A group, the B group, and the C group into two frequency channels (Fx and Fy) and using the acquisition timings of the A0, B0, and C0 slots, respectively, the flying object On the other hand, at the time of handover, it is possible to provide a stable wireless environment and maintain a certain amount of communication. Further, the flying object 100 increases the amount of data to be transmitted on the frequency channel Fx after the synchronization on the frequency channel Fx used in the coverage area of the movement destination can be established. In other words, after confirming that the data communication of the group C is possible, the processing is changed so that the slot of the group B that has been handled together with the group A is handled together with the slot of the group C.

  As a modulation method used in the processing, a strong modulation method (modulation method having high stability) is selected as the modulation method of the C group to be handed over first, and the modulation method of the B group to be handed over later is selected. A high-speed modulation method (a modulation method giving priority to high-speed communication) may be selected.

  The modulation method changing process may be selected based on the radio field strength between the flying object and each base station, the positional relationship between the flying object and the base station, and the change direction of the position between the flying object and the base station. good. Further, the modulation method or the like may be selectable at the central station.

FIG. 11 shows a case (normal state) belonging to only one coverage area after the handover process.
The X base station 21 broadcasts NTR information at the timings of the A0, B0, and C0 slots using Fx, which is a used frequency channel.
The flying object 100 identifies the covered area P based on the instruction from itself or the central station 10 and receives it using the frequency channel Fx used by the base station 21 at the timing of all the A0, B0, and C0 slots. The system synchronization timing of each of slot A group, B group, and C group is acquired.

  As a result, the flying object 100 can transmit / receive data to / from the central station 10 via the X base station 21 in all slots of the A group, the B group, and the C group using the acquisition timings of the A0, B0, and C0 slots, respectively. And

  After receiving the A0, B0, and C0 slots, the same information is acquired three times, so that stable communication may be performed, or different information may be communicated to increase the amount of information.

  As described above with reference to FIGS. 8 to 11, the TDMA format frame is divided into a predetermined number of time slot groups, and a synchronization time slot is provided for each time slot group, so that a plurality of TDMA format frames can be synchronized. System synchronization information for measuring the synchronization timing with its own station is inserted into all time slots for each slot group, and transmitted using the frequency channel to be used. Using the synchronization information, it is possible to perform system synchronization with the belonging base station and the destination base station.

  Further, as in the above operation example, after the handover process is started, the flying object 100 performs the scan reception of the synchronization time slot having 3 slots by using the source frequency channel and the destination frequency channel. At the same time, it is divided and executed so that the number of destination frequency channels increases. As a result, it is possible to realize a more stable handover process than estimating the movement to the coverage area of the movement destination and immediately starting reception using the frequency channel of the movement destination.

  In addition, when the flying object 100 is located around the boundary of the coverage area of the base stations 21, 22, and 23, and the central station cannot easily estimate which base station the communication is good by moving, The flying object 100 starts the switching process, receives the frequency channel Fy used by the base station 22 at the timing of the time slot A0, acquires the system synchronization timing of the slot A group, and also acquires the time slot B0. The frequency channel Fx used by the base station 21 is awaited and received at the timing, the system synchronization timing of the slot B group is obtained, and the frequency channel Fz used by the base station 23 is obtained at the timing of the time slot C0. By receiving, it is possible to select a base station with good reception for each superframe and maintain a good communication state.

  As described above, by using the TDMA communication system of the present invention, it is possible to provide a TDMA communication system that can provide a high-speed and stable wireless environment to a flying object.

More specifically, it is possible to provide a TDMA communication system that is not easily affected by radio wave delay in the coverage area.
Further, the flying object can communicate with different base stations (frequency channels) in any slot by acquiring the synchronization timing of each slot of the frame.
In addition, it is possible to provide a TDMA communication system that can be synchronized with multiple base stations in a plurality of frequency channels.
In addition, it is possible to provide a TDMA communication system that is not easily affected by fading due to the sea surface or mountains.
In addition, it is possible to perform handover with respect to coverages having different use frequency channels with the radio link connected.
The above effect is an effect that cannot be provided by the existing TDMA communication system in contrast to the high-speed movement of the flying object.

It should be noted that the specific configuration of the present invention is not limited to the above-described embodiment, and modifications within a range not departing from the gist of the present invention are included in the present invention.
For example, the number of superframe slots and the number of slot groups may be increased or decreased.
Further, the order of slot groups to be switched at the time of handover is also arbitrary.
Further, the base station may not be a fixed station but a mobile station (a ship, a vehicle, an aircraft relay station).
If the location information and delay time of each base station are clear, calculate the delay of data transmitted from the central station to the flying object until transmission from the base station, cancel the delay, and then May be provided in the base station and the central station.

10 Central station 21 Base station (subordinate station)
22 Base station (dependent station)
23 Base station (dependent station)
100 flying object (mobile station)

Claims (8)

A predetermined number of time slots are divided into a plurality of slot groups, the time slots of the slot groups are distributed so as to be adjacent to different time slots, and the synchronization time slots of the slot groups are arranged side by side at the beginning of the frame. The TDMA frame format is used to configure a plurality of base stations that construct a coverage area, a central station that controls the plurality of base stations and communicates with the flying object, and one or more flying objects ,
System synchronization information is transmitted from the plurality of base stations to all the synchronization time slots of the slot group,
The flying object is
The frequency channel of the TDMA radio is set for each slot group, and the system synchronization information included in each synchronization time slot is acquired.
At the time of handover to switch the base station used for communication with the central station, transmitted from each base station that constructs the belonging coverage area and the destination coverage area included in each of the plurality of synchronization time slots. The system synchronization information is detected using a plurality of synchronization time slots, and the handover is completed through the process of dividing the plurality of slot groups and enabling communication with the central station via both base stations <br / > A TDMA communication system for a flying object. In a TDMA communication system for a flying object using the TDMA frame format according to claim 1,
System synchronization information is transmitted from the plurality of base stations to all the synchronization time slots of the slot group using a frequency channel for each base station,
The flying object sets a use frequency channel of the TDMA radio for each slot group, detects system synchronization information included in each synchronization time slot with at least one frequency channel, and detects the detected system synchronization A flying object TDMA communication system characterized in that information of a superframe itself and unique information regarding remaining time slots in the same superframe are acquired from the information and communicated. In a TDMA communication system for a flying object using the TDMA frame format according to claim 1 or 2,
The system synchronization information includes information indicating the data length of the slot,
When the flying object detects system synchronization information from individual synchronization time slots, the flying object identifies data lengths used in the plurality of slot groups to identify data of individual slots. TDMA communication system for flying objects. A TDMA communication system for a flying object according to any one of claims 1 to 3 ,
After the start of the handover process, the flying object scans each of the plurality of synchronization time slots by switching the frequency channel used by the TDMA radio each time, and performing the scan on the source frequency channel and the destination frequency channel, respectively. A TDMA communication system for a flying object. A flying object TDMA communication system according to any one of claims 1 to 4 ,
3 or more slots for synchronization are provided,
After the start of the handover process, the flying object scans each of the synchronization time slots of 3 slots or more into the movement source frequency channel and the movement destination frequency channel, and the movement destination frequency channel is changed as the handover process proceeds. A TDMA communication system for a flying object, which is divided and implemented so as to increase. A predetermined number of time slots are divided into a plurality of slot groups, and a TDMA format frame in which a synchronization time slot is provided for each slot group is synchronized using time.
All of the plurality of synchronization time slots included in the TDMA format frame are detected using the frequency channels used in the coverage area, and the system synchronization information for each slot group is obtained from each synchronization time slot. Get each
Based on the system synchronization information for each slot group, one or more base stations to be wirelessly connected and information on the superframe itself and unique information on the remaining time slots in the same superframe are specified .
With
At the time of handover to switch base stations used for communication when communicating with a central station that supervises a plurality of base stations,
Detecting system synchronization information transmitted from each base station that constructs the belonging coverage area and the destination coverage area included in each of the plurality of synchronization time slots using a plurality of synchronization time slots The flying object is characterized by completing a handover through a process of dividing a plurality of slot groups and enabling communication with the central station via both base stations . The flying object according to claim 6 ,
After the handover process is started, each scan of the plurality of synchronization time slots is performed by switching the frequency channel used by the TDMA radio unit each time and dividing the scan frequency slot into a source frequency channel and a destination frequency channel. A flying object characterized by A predetermined number of time slots are divided into a plurality of slot groups, the time slots of the slot groups are distributed so as to be adjacent to different time slots, and the synchronization time slots of the slot groups are arranged side by side at the beginning of the frame. The TDMA frame format is used by a plurality of base stations and flying objects that construct coverage,
When the flying body communicates with the central station that supervises the plurality of base stations,
System synchronization information is transmitted from the plurality of base stations to all the synchronization time slots of the slot group,
The flying object is
The frequency channel of the TDMA radio is set for each slot group, and the system synchronization information included in each synchronization time slot is acquired.
At the time of handover to switch the base station used for communication with the central station, transmitted from each base station that constructs the belonging coverage area and the destination coverage area included in each of the plurality of synchronization time slots. The system synchronization information is detected using a plurality of synchronization time slots, and the handover is completed through a process of dividing a plurality of slot groups and enabling communication with the central station via both base stations.
A TDMA communication method for a flying object.

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