Access point and wireless communication system

Abstract

To reduce processing loads when multiple access points communicate with a communication terminal.SOLUTION: An access point 2 includes a storage unit 23 that stores main preamble data assigned to the access point 2 and sub-preamble data assigned to another access point, a terminal side transmitter 211 that transmits the main preamble data to a communication terminal 3, a terminal side receiver 212 that receives the terminal preamble data and terminal identification information for identifying the communication terminal 3 from the communication terminal 3, and a control unit 24 that controls a network side transmitter 221 to transmit the terminal identification information to a communication control device 1 when the terminal preamble data corresponds to either the main preamble data or the sub-preamble data stored in the storage unit 23.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to an access point and a wireless communication system. [Background technology]

[0002] Conventionally, a technology is known in which a communication terminal (UE) performs data communication with a plurality of access points (APs). Patent Document 1 discloses a method of notifying control information for making an access point recognize a communication terminal when the communication terminal performs data communication with the access point.

[0003] Patent Document 1 discloses a case where multiple access points are set with a common cell ID and preamble data and operate in cooperation with each other, and a case where multiple access points do not cooperate with each other. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] US Patent Publication No. 2018 / 0235013 Summary of the Invention [Problem to be solved by the invention]

[0005] When multiple access points operate in cooperation with each other, the load of transmitting and receiving control information for cooperation between the multiple access points increases as the number of access points that communicate with one communication terminal increases.On the other hand, when multiple access points do not operate in cooperation with each other, the communication terminal needs to perform processing (e.g., 4-step RACH processing) to establish a wireless communication link with each of the multiple access points, which increases the load on the communication terminal.

[0006] The present invention has been made in view of these points, and has as its object to reduce the processing load when a communication terminal communicates with a plurality of access points. [Means for solving the problem]

[0007] An access point of a first aspect of the present invention is an access point that communicates with a communication control device and a communication terminal, and includes: a memory unit that stores main preamble data assigned to the access point and secondary preamble data assigned to another access point; a terminal-side transmitter unit that transmits the main preamble data to the communication terminal; a terminal-side receiver unit that receives the terminal preamble data and terminal identification information for identifying the communication terminal from the communication terminal; and a control unit that controls the network-side transmitter unit to transmit the terminal identification information to the communication control device when the terminal preamble data corresponds to either the main preamble data or the secondary preamble data stored in the memory unit.

[0008] The network-side transmitting unit may transmit, together with the terminal identification information, time data indicating a time at which the terminal preamble data was received to the communication control device.

[0009] When the terminal preamble data received from the communication terminal corresponds to the main preamble data, the network-side transmitting unit may transmit notification data to the communication control device indicating that the terminal preamble data corresponding to the main preamble data has been received.

[0010] The control unit may store the terminal identification information in the memory unit when the terminal preamble data received from the communication terminal corresponds to the main preamble data or the secondary preamble data stored in the memory unit.

[0011] The control unit may control the terminal-side transmitting unit to execute a process of establishing a communication link with the communication terminal when the terminal preamble data received from the communication terminal corresponds to the main preamble data stored in the memory unit.

[0012] The control unit may also control the terminal-side receiving unit to receive data transmitted and received while another access point is performing a process to establish a communication link with the communication terminal when the terminal preamble data received from the communication terminal corresponds to the secondary preamble data stored in the memory unit.

[0013] The access point may further have a network-side receiving unit that receives scheduling information from the communication control device after the network-side transmitting unit transmits the terminal identification information to the communication control device, the scheduling information specifying the timing and frequency for transmitting data to the communication terminal, and the control unit may control the terminal-side transmitting unit to transmit data to the communication terminal based on the scheduling information.

[0014] A wireless communication system of a second aspect of the present invention comprises a communication control device, a plurality of access points, and a communication terminal communicating with the plurality of access points, wherein each of the plurality of access points has a memory unit that stores primary preamble data assigned to the access point and secondary preamble data assigned to other access points, a terminal-side transmitter that transmits the primary preamble data to the communication terminal, a terminal-side receiver that receives the terminal preamble data and terminal identification information for identifying the communication terminal from the communication terminal, and a control unit that controls the network-side transmitter to transmit the terminal identification information to the communication control device when the terminal preamble data corresponds to either the primary preamble data or the secondary preamble data stored in the memory unit, and the communication terminal has a terminal receiver that receives the primary preamble data transmitted by the plurality of access points, and a terminal transmitter that transmits the terminal preamble data corresponding to any of the primary preamble data received by the terminal receiver.

[0015] The communication control device may have an information creation unit that creates scheduling information for the multiple access points to communicate data with the communication terminal in response to receiving the terminal identification information from the network side transmission unit of each of the multiple access points, and an information transmission unit that transmits the scheduling information to the multiple access points. [Effects of the Invention]

[0016] According to the present invention, it is possible to reduce the processing load when a communication terminal communicates with a plurality of access points. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a diagram for explaining an overview of a wireless communication system S. [Figure 2] FIG. 1 is a diagram for explaining an overview of a wireless communication system S. [Figure 3] FIG. 1 is a diagram for explaining an overview of a wireless communication system S. [Figure 4] FIG. 1 is a diagram for explaining an overview of a wireless communication system S. [Figure 5] 1 is a diagram illustrating a configuration of a communication control device 1. FIG. [Figure 6] FIG. 2 is a diagram showing a configuration of a communication terminal 3. [Figure 7] FIG. 2 is a diagram illustrating a configuration of an access point 2. [Figure 8] 10 is a flowchart showing the flow of processing at the access point 2. [Figure 9] 1 is a sequence diagram showing a processing flow in a wireless communication system S. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] [Overview of Wireless Communication System S] 1 to 4 are diagrams illustrating an overview of a wireless communication system S. The wireless communication system S includes a communication control device 1, multiple access points 2, and multiple communication terminals 3. The wireless communication system S is a mobile communication system that enables the communication terminals 3 to communicate with other communication terminals 3 via a network. The wireless communication system S is a system that enables data communication between the communication terminals 3 without forming fixed cells, by having the communication terminals 3 transmit and receive data to and from the multiple access points 2 and having the multiple access points 2 transmit and receive data to and from the communication control device 1.

[0019] The communication control device 1 is a computer managed by a carrier that operates a mobile communication system, and is, for example, a CU (Central Unit) in 5G. The communication control device 1 transmits and receives data to and from a plurality of access points 2, and also communicates with other devices via a network.

[0020] The communication terminal 3 is a mobile information terminal, such as a smartphone, tablet, personal computer, or IoT (Internet of Things) device. The communication terminal 3 transmits and receives data to and from the communication control device 1 via the multiple access points 2 by using the multiple access points 2 as MIMO (Multi-Input Multi-Output) antenna ports. When the communication terminal 3 establishes wireless communication links with the multiple access points 2, a cluster including the multiple access points 2 is formed.

[0021] The multiple access points 2 are configured to be able to communicate with the communication control device 1 and the communication terminal 3. The multiple access points 2 are connected to the communication control device 1 by wire, for example, but may also be connected to the communication control device 1 wirelessly.

[0022] Each of the multiple access points 2 stores primary preamble data set therefor, and transmits the primary preamble data when establishing a wireless communication link with the communication terminal 3. The access point 2 transmits the primary preamble data using, for example, SS / PBCH (Synchronization Signal / Physical Broadcast Channel), which is an example of a broadcast signal.

[0023] The access point 2 stores the primary preamble data of other nearby access points 2 as its own secondary preamble data. The access point 2 stores the primary preamble data of other access points 2 notified by, for example, the communication control device 1 as secondary preamble data.

[0024] The access point 2 determines whether the terminal preamble data transmitted by the communication terminal 3 corresponds to either the main preamble data or the secondary preamble data, and switches the subsequent processing depending on whether the terminal preamble data corresponds to the main preamble data or the secondary preamble data.

[0025] An overview of the wireless communication system S will be described below with reference to Figures 1 to 4. Although four access points 2 and one communication terminal 3 are shown in Figures 1 to 4, the number of access points 2 and communication terminals 3 is arbitrary.

[0026] 1, "P:1" displayed below access point 2-1 indicates that access point 2-1 stores preamble data 1 (hereinafter sometimes referred to as "PR1") as its primary preamble data. "S:2" indicates that access point 2-1 stores preamble data 2 (hereinafter sometimes referred to as "PR2"), which is the primary preamble data of nearby access point 2-2, as its secondary preamble data.

[0027] "P:2" displayed below the access point 2-2 indicates that the access point 2-2 stores PR2 as the primary preamble. "S:1, 3" indicates that the access point 2-2 stores PR1, which is the primary preamble data of the nearby access point 2-1, and preamble data 3 (hereinafter sometimes referred to as "PR3"), which is the primary preamble data of the access point 2-3, as secondary preamble data.

[0028] Similarly, "P:3" displayed below the access point 2-3 indicates that the access point 2-3 stores PR3 as its primary preamble data. "S:2, 4" indicates that the access point 2-3 stores PR2, which is the primary preamble data of the nearby access point 2-2, and preamble data 4 (hereinafter sometimes referred to as "PR4"), which is the primary preamble data of the access point 2-4, as secondary preamble data.

[0029] 1, first, in a state where no cluster is formed, multiple access points 2 transmit broadcast signals including stored main preamble data. Specifically, access points 2-1 to 2-4 transmit broadcast signals including PR1 to PR4, respectively. Communication terminal 3 receives these broadcast signals.

[0030] The communication terminal 3 selects the access point 2 that has transmitted the beacon signal that satisfies a predetermined condition from among the received beacon signals. This predetermined condition may be, for example, the highest received signal level, but the predetermined condition is not limited to this and may be a combination of multiple conditions. In this example, it is assumed that the beacon signal containing PR2 has the highest received signal level, and the communication terminal 3 has selected the access point 2-2.

[0031] In this case, as shown in Fig. 2, the communication terminal 3 transmits a signal including PR2 as terminal preamble data in order to establish a wireless communication link with the access point 2-2. The terminal preamble data is preamble data included in data transmitted by the communication terminal 3. The wireless communication link establishment process is, for example, a 4-step Random Access Channel (RACH) process, and the communication terminal 3 transmits an Msg 1 signal including PR2 as Msg 1 in the 4-step RACH process. The Msg 1 signal includes a UE-ID, which is terminal identification information for identifying the communication terminal 3.

[0032] The access points 2 receive the signal including the PR2 and compare it with the main preamble data and secondary preamble data stored therein. If the received PR2 corresponds to either the main preamble data or the secondary preamble data stored therein, the access point 2 transmits to the communication control device 1 the UE-ID included in the received Msg 1 signal and reception timing data indicating the timing at which the Msg 1 signal was received.

[0033] The case where the received PR2 corresponds to either the main preamble data or the secondary preamble data stored by the access point 2 means that it can be identified that the received PR2 was created based on either the main preamble data or the secondary preamble data stored by the access point 2, for example, when the received PR2 matches either the main preamble data or the secondary preamble data. If the received PR2 does not correspond to either the main preamble data or the secondary preamble data stored by the access point 2, the access point 2 ends the process without transmitting the UE-ID and the reception timing data to the communication control device 1.

[0034] 3, access point 2-2, whose PR2 included in the Msg 1 signal corresponds to its own primary preamble data, and access point 2-1 and access point 2-3, whose PR2 included in the Msg 1 signal corresponds to their own secondary preamble data, transmit UE-IDs to the communication control device 1. The timing at which the access point 2 transmits the UE-ID is arbitrary, but for example, multiple access points 2 transmit UE-IDs between the time they receive terminal preamble data from the communication terminal 3 and the time the 4-step RACH processing between the access point 2-2 and the communication terminal 3 is completed.

[0035] For example, the multiple access points 2 transmit the UE-ID at the timing when it is expected that the access point 2-2 selected by the communication terminal 3 will complete the 4-step RACH process. The multiple access points 2 may transmit the UE-ID while the access point 2-2 is performing the 4-step RACH process, or may monitor the data being transmitted and received in the 4-step RACH process and transmit the UE-ID at the timing when the 4-step RACH process is completed.

[0036] The access point 2-2 receives its own main preamble data PR2 from the communication terminal 3 and exchanges Msg 2 and subsequent steps of the 4-step RACH processing, thereby establishing a wireless communication link between the access point 2-2 and the communication terminal 3. When the 4-step RACH processing is completed, the access point 2-2 notifies the communication control device 1 that a wireless communication link has been established. By observing the 4-step RACH processing performed between the access point 2-2 and the communication terminal 3, the access point 2-1 and the access point 2-3 recognize that a wireless communication link between the access point 2-2 and the communication terminal 3 has been established.

[0037] Next, as shown in FIG. 4 , the communication control device 1 creates scheduling information to be notified to each of the three access points 2, namely, the access point 2-2, and the access points 2-1 and 2-3 that received the UE-ID from the communication terminal 3 at approximately the same timing as the access point 2-2, so that the three access points 2 can transmit and receive data to and from the communication terminal 3. The scheduling information includes the frequency and time (slot) to be allocated to each access point 2, as well as precoding coefficients to be used in the download link. The communication control device 1 notifies the access point 2-1, access point 2-2, and access point 2-3 of the scheduling information. The access point 2-2 transmits the notified scheduling information to the communication terminal 3.

[0038] Thereafter, the multiple access points 2 and communication terminal 3 start data communication based on the scheduling information. Specifically, communication terminal 3 transmits data at a frequency and time when access point 2-1, access point 2-2, and access point 2-3 can receive data, and receives data at a frequency and time when access point 2-1, access point 2-2, and access point 2-3 can transmit data. The configurations and operations of the communication control device 1, access point 2, and communication terminal 3 will be described in detail below.

[0039] [Configuration of communication control device 1] 5 is a diagram showing the configuration of the communication control device 1. The communication control device 1 has an information receiving unit 11, an information transmitting unit 12, a storage unit 13, and a device control unit .

[0040] The information receiving unit 11 receives various types of information from the plurality of access points 2. The information receiving unit 11 receives, for example, UE-IDs received by the plurality of access points 2 from communication terminals 3 with which the plurality of access points 2 are to communicate.

[0041] The information transmitting unit 12 transmits various types of information to the plurality of access points 2. The information transmitting unit 12 transmits, for example, scheduling information created by the device control unit 14 to the plurality of access points 2.

[0042] The storage unit 13 has storage media such as a read-only memory (ROM), a random access memory (RAM), and a solid-state drive (SSD). The storage unit 13 stores programs executed by the device control unit 14. The storage unit 13 also stores scheduling information corresponding to each of the multiple access points 2.

[0043] The device control unit 14 has, for example, a CPU (Central Processing Unit), and executes programs stored in the storage unit 13 to realize various functions executed by the communication control device 1. The device control unit 14 functions, for example, as an information creation unit that creates scheduling information in response to the information receiving unit 11 receiving UE-IDs from each of the multiple access points 2.

[0044] [Configuration of communication terminal 3] 6 is a diagram showing the configuration of the communication terminal 3. The communication terminal 3 has a terminal receiving unit 31, a terminal transmitting unit 32, a storage unit 33, and a terminal control unit .

[0045] The terminal receiving unit 31 receives various types of information from the multiple access points 2. The terminal receiving unit 31 receives, for example, main preamble data transmitted by the multiple access points 2.

[0046] The terminal transmitter 32 transmits various types of information to the multiple access points 2. For example, the terminal transmitter 32 transmits terminal preamble data corresponding to one of the multiple pieces of main preamble data received by the terminal receiver 31 using a Random Access Channel (RACH). Specifically, for example, the terminal transmitter 32 transmits terminal preamble data corresponding to the main preamble data received from an access point 2 selected by the terminal controller 34 from the multiple access points 2. The terminal preamble data may be data that matches the main preamble data, or may be data created by converting the main preamble data based on a predetermined conversion rule.

[0047] The storage unit 33 has storage media such as a ROM and a RAM, etc. The storage unit 33 stores a program executed by the terminal control unit 34. The storage unit 33 also stores a UE-ID.

[0048] The terminal control unit 34 has, for example, a CPU, and executes programs stored in the storage unit 33 to realize various functions executed by the communication terminal 3. The terminal control unit 34 selects one access point 2, for example, based on the level of the signal received by the terminal receiving unit 31 from each of the multiple access points 2. The terminal control unit 34 creates terminal preamble data corresponding to the main preamble data received from the selected access point 2, and causes the terminal transmitting unit 32 to transmit the created terminal preamble data.

[0049] [Access Point 2 Configuration] 7 is a diagram showing the configuration of the access point 2. The access point 2 has a terminal-side communication unit 21, a network-side communication unit 22 (hereinafter referred to as “NW-side communication unit 22”), a storage unit 23, and a control unit 24.

[0050] The terminal-side communication unit 21 includes a device that executes communication processing for transmitting and receiving data to and from the communication terminal 3, and has a terminal-side transmission unit 211 and a terminal-side reception unit 212. The terminal-side transmission unit 211 and the terminal-side reception unit 212 operate under the control of the control unit 24. The terminal-side transmission unit 211 and the terminal-side reception unit 212 operate in cooperation with each other to execute 4-step RACH processing with the communication terminal 3.

[0051] The terminal-side transmitter 211 functions as, for example, a terminal-side transmitter that transmits a broadcast signal including main preamble data stored in the storage unit 23. When the access point 2 performs 4-step RACH processing with the communication terminal 3, the terminal-side transmitter 211 transmits an Msg 2 signal and an Msg 4 signal to the communication terminal 3. After a wireless communication link with the communication terminal 3 is established, the terminal-side transmitter 211 also transmits to the communication terminal 3 data that the communication control device 1 transmitted to the communication terminal 3.

[0052] The terminal-side receiving unit 212 receives various data from the communication terminal 3. For example, the terminal-side receiving unit 212 receives terminal preamble data and terminal identification information for identifying the communication terminal 3 from the communication terminal 3. When the access point 2 performs 4-step RACH processing with the communication terminal 3, the terminal-side receiving unit 212 receives the Msg 1 signal and the Msg 3 signal transmitted by the communication terminal 3. After a wireless communication link with the communication terminal 3 is established, the terminal-side receiving unit 212 receives data transmitted by the communication terminal 3 to the communication control device 1, and notifies the control unit 24 of the received data.

[0053] The NW-side communication unit 22 includes a device that executes communication processing for transmitting and receiving data to and from the communication control device 1, and has a network-side transmitting unit 221 (hereinafter referred to as the “NW-side transmitting unit 221”) and a network-side receiving unit 222 (hereinafter referred to as the “NW-side receiving unit 222”). The NW-side transmitting unit 221 and the NW-side receiving unit 222 operate under the control of the control unit 24.

[0054] When the terminal preamble data received from the communication terminal 3 corresponds to either the main preamble data or the secondary preamble data stored in the memory unit 23, the NW side transmitting unit 221 transmits the UE-ID of the communication terminal 3 and time data indicating the time when the terminal preamble data was received to the communication control device 1.

[0055] When the terminal preamble data received from the communication terminal 3 corresponds to the main preamble data, the NW-side transmitting unit 221 may transmit notification data indicating that the terminal preamble data corresponding to the main preamble data has been received, to the communication control device 1. When the terminal preamble data received from the communication terminal 3 corresponds to the secondary preamble data, the NW-side transmitting unit 221 may transmit notification data indicating that the terminal preamble data corresponding to the secondary preamble data has been received, to the communication control device 1. After the wireless communication link between the access point 2 and the communication terminal 3 is established, the NW-side transmitting unit 221 transmits the data received from the communication terminal 3 and addressed to the communication control device 1 to the communication control device 1.

[0056] The NW-side receiving unit 222 receives data transmitted from the communication control device 1. For example, the NW-side receiving unit 222 receives, from the communication control device 1, scheduling information that specifies the timing and frequency for transmitting data to the communication terminal 3. The NW-side receiving unit 222 notifies the control unit 24 of the received scheduling information. The NW-side receiving unit 222 may store the received scheduling information in the storage unit 23.

[0057] The storage unit 23 has storage media such as a ROM (Read Only Memory), a RAM (Random Access Memory), and an SSD (Solid State Drive). The storage unit 23 stores programs executed by the control unit 24. The storage unit 23 also stores primary preamble data assigned to the access point 2 and secondary preamble data assigned to other access points 2. The storage unit 23 also stores various data used by the access point 2 to relay data transmitted and received between the communication control device 1 and the communication terminal 3.

[0058] The control unit 24 has, for example, a CPU (Central Processing Unit). The control unit 24 executes a program stored in the storage unit 23 to establish a wireless communication link with the communication terminal 3 and to perform various processes for relaying data transmitted and received between the communication control device 1 and the communication terminal 3.

[0059] The control unit 24 controls the operations of the terminal-side transmitting unit 211, the terminal-side receiving unit 212, the NW-side transmitting unit 221, and the NW-side receiving unit 222. For example, the control unit 24 notifies the terminal-side transmitting unit 211 of the main preamble data stored in the storage unit 23 and controls the terminal-side transmitting unit 211 to transmit a broadcast signal including the main preamble data. Furthermore, the control unit 24 controls the NW-side transmitting unit 221 to transmit a UE-ID to the communication control device 1 when the terminal preamble data received from the communication terminal 3 corresponds to either the main preamble data or the secondary preamble data stored in the storage unit 23.

[0060] When the terminal preamble data received from the communication terminal 3 corresponds to the main preamble data or the secondary preamble data stored in the memory unit 23, the control unit 24 may store the UE-ID, which is terminal identification information for identifying the communication terminal 3, in the memory unit 23.

[0061] When the terminal preamble data received from the communication terminal 3 corresponds to the primary preamble data stored in the storage unit 23, the control unit 24 controls the terminal-side transmitting unit 211 to execute processing to establish a wireless communication link with the communication terminal 3. When the terminal preamble data received from the communication terminal 3 corresponds to the secondary preamble data stored in the storage unit 23, the control unit 24 controls the terminal-side receiving unit 212 to receive data transmitted and received while another access point 2 executes processing to establish a wireless communication link with the communication terminal 3.

[0062] The control unit 24 controls the terminal-side transmitting unit 211 so that the NW-side receiving unit 222 transmits data to the communication terminal 3 based on the scheduling information received from the communication control device 1. The control unit 24 controls the terminal-side receiving unit 212 so that the NW-side receiving unit 222 receives data from the communication terminal 3 based on the scheduling information. For example, when the UE-ID included in the scheduling information corresponds to the UE-ID stored in the storage unit 23, the control unit 24 controls the terminal-side transmitting unit 211 and the terminal-side receiving unit 212 so that data is transmitted and received between the communication terminal 3 and the NW-side receiving unit 222 and the communication terminal 3 based on the frequency and time included in the scheduling information.

[0063] [Processing flow at access point 2] 8 is a flowchart showing the flow of processing at the access point 2. The flowchart shown in FIG.

[0064] The control unit 24 controls the terminal-side transmitting unit 211 to transmit a notification signal including the main preamble data stored in the storage unit 23 (S1). The control unit 24 causes the terminal-side transmitting unit 211 to transmit the notification signal, for example, periodically. Thereafter, the control unit 24 determines whether the terminal-side receiving unit 212 has received the main preamble data from the communication terminal 3 (S2). Specifically, the control unit 24 determines whether the terminal preamble data received by the terminal-side receiving unit 212 from the communication terminal 3 corresponds to the main preamble data transmitted by the terminal-side transmitting unit 211.

[0065] When the terminal-side receiving unit 212 receives the main preamble data transmitted by the terminal-side transmitting unit 211 from the communication terminal 3 (YES in S2), the control unit 24 stores the UE-ID of the access point 2 that transmitted the terminal preamble data corresponding to the main preamble data in the storage unit 23 (S3). The control unit 24 transmits the UE-ID and the time when the UE-ID was received to the communication control device 1 (S4).

[0066] Furthermore, the control unit 24 executes a process for establishing a wireless communication link with the communication terminal 3 (S5). Specifically, the control unit 24 executes a 4-step RACH process with the communication terminal 3. When the process for establishing the wireless communication link is completed, the control unit 24 transmits a connection completion notification to the communication control device 1 (S6). Note that the control unit 24 may execute a process for transmitting the UE-ID and the reception time of S4 after executing the process for establishing the wireless communication link.

[0067] If the control unit 24 determines in S2 that the primary preamble data has not been received from the communication terminal 3 (NO in S2), the control unit 24 determines whether or not the secondary preamble data has been received from the communication terminal 3 (S7). Specifically, the control unit 24 determines whether or not the terminal preamble data received by the terminal-side receiving unit 212 from the communication terminal 3 corresponds to the secondary preamble data stored in the storage unit 23.

[0068] When the terminal-side receiving unit 212 receives the secondary preamble data stored in the storage unit 23 from the communication terminal 3 (YES in S7), the control unit 24 stores the UE-ID of the access point 2 that transmitted the terminal preamble data corresponding to the secondary preamble data in the storage unit 23 (S8). The control unit 24 transmits the UE-ID and the time when the UE-ID was received to the communication control device 1 (S9).

[0069] Thereafter, after the process of S6 or S9, the control unit 24 receives scheduling information from the communication control device 1 via the NW-side receiving unit 222 (S10). The control unit 24 transmits and receives data to and from the communication terminal 3 based on the frequency and timing included in the scheduling information (S11). The control unit 24 transmits and receives data to and from the communication terminal 3 until, for example, a control signal for terminating communication is received from the communication control device 1 or the communication terminal 3 (NO in S12).

[0070] [Processing flow in wireless communication system S] 9 is a sequence diagram showing the flow of processing in the wireless communication system S. In Fig. 9, "CPU" represents the communication control device 1, "AP" represents the access point 2, and "UE" represents the communication terminal 3. The processing shown in Fig. 9 starts from a state in which the communication terminal 3 is not connected to the access point 2.

[0071] Each of the multiple access points 2 periodically transmits a broadcast signal including main preamble data stored in its own storage unit 23. When the communication terminal 3 receives main preamble data transmitted from the multiple access points 2, it selects one access point 2 based on predetermined conditions. For example, the communication terminal 3 selects the access point 2 with the highest broadcast signal reception level (i.e., the access point 2 with the smallest transmission path loss). In FIG. 9, the communication terminal 3 selects the access point 2-2.

[0072] The communication terminal 3 transmits PR2, which is the main preamble data transmitted by the selected access point 2-2, as terminal preamble data. The multiple access points 2 receive the terminal preamble data.

[0073] Of the multiple access points 2, access point 2-2 transmits the UE-ID of communication terminal 3 to the communication control device 1 because the terminal preamble data corresponds to the primary preamble data stored in storage unit 23. Access point 2-1 and access point 2-3 transmit the UE-ID of communication terminal 3 to the communication control device 1 because the terminal preamble data corresponds to the secondary preamble data stored in storage unit 23. Access point 2-4 does not transmit the UE-ID of communication terminal 3 to the communication control device 1 because the terminal preamble data does not correspond to either the primary preamble data or the secondary preamble data stored in storage unit 23.

[0074] The access point 2-2 executes a 4-step RACH process, which is a process for establishing a wireless link with the communication terminal 3. Upon completion of the 4-step RACH process, the access point 2-2 transmits a connection completion notification to the communication control device 1. Thereafter, the communication control device 1 creates scheduling information and transmits the scheduling information to the access points 2-1, 2-2, and 2-3 that transmitted the UE-ID. This allows the communication terminal 3 to transmit and receive data to and from the communication control device 1 via the access points 2-1, 2-2, and 2-3.

[0075] [Effects of Access Point 2] As described above, the access point 2 according to this embodiment transmits a broadcast signal including the primary preamble data stored in the storage unit 23, and when the terminal preamble data received from the communication terminal 3 corresponds to either the primary preamble data or the secondary preamble data stored in the storage unit 23, forms a cluster by transmitting the UE-ID of the communication terminal 3 that transmitted the terminal preamble data to the communication control device 1. Furthermore, when the terminal preamble data corresponds to the primary preamble data, the access point 2 executes processing to establish a wireless communication link with the communication terminal 3. By configuring the access point 2 in this way, it becomes possible for the communication terminal 3 to communicate with multiple access points 2 while suppressing an increase in the processing load when multiple access points 2 and the communication terminal 3 communicate with each other.

[0076] Furthermore, this invention will make it possible to contribute to Goal 9 of the United Nations' Sustainable Development Goals (SDGs), which is "Build resilient infrastructure, promote inclusive and sustainable industrialization, and promote innovation and resilience."

[0077] The present invention has been described above using embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. For example, all or part of the device can be configured by functionally or physically distributing or integrating any unit. Furthermore, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effects of the new embodiments resulting from the combination also have the effects of the original embodiments. [Explanation of symbols]

[0078] 1. Communication control device 2. Access points 3. Communication terminals 11 Information Receiving Unit 12 Information transmission unit 13 Storage section 14 Device control section 21 Terminal communication unit 22 Network side communication unit 23 Memory section 24 Control Unit 31 Terminal receiving unit 32 Terminal transmitter 33 Storage section 34 Terminal control unit 211 Terminal side transmission unit 212 Terminal side receiving unit 221 Network side transmitter 222 Network side receiving unit

Claims

1. An access point that communicates with a communication control device and a communication terminal, a storage unit that stores primary preamble data assigned to the access point and secondary preamble data assigned to other access points; a terminal side transmitting unit that transmits the main preamble data to the communication terminal; a terminal side receiving unit that receives terminal preamble data and terminal identification information for identifying the communication terminal from the communication terminal; a control unit that controls a network-side transmitting unit to transmit, to the communication control device, time data indicating a time when the terminal preamble data corresponds to either the main preamble data or the secondary preamble data stored in the storage unit, together with the terminal identification information; An access point having

2. An access point that communicates with a communication control device and a communication terminal, a storage unit that stores primary preamble data assigned to the access point and secondary preamble data assigned to other access points; a terminal side transmitting unit that transmits the main preamble data to the communication terminal; a terminal side receiving unit that receives terminal preamble data and terminal identification information for identifying the communication terminal from the communication terminal; a control unit that controls a network-side transmitting unit to transmit the terminal identification information to the communication control device when the terminal preamble data corresponds to either the main preamble data or the secondary preamble data stored in the storage unit; and When the terminal preamble data received from the communication terminal corresponds to the main preamble data, the network-side transmitting unit transmits notification data indicating that the terminal preamble data corresponding to the main preamble data has been received to the communication control device. Access point.

3. An access point that communicates with a communication control device and a communication terminal, a storage unit that stores primary preamble data assigned to the access point and secondary preamble data assigned to other access points; a terminal side transmitting unit that transmits the main preamble data to the communication terminal; a terminal side receiving unit that receives terminal preamble data and terminal identification information for identifying the communication terminal from the communication terminal; a control unit that controls a network-side transmitting unit to transmit the terminal identification information to the communication control device when the terminal preamble data corresponds to either the main preamble data or the secondary preamble data stored in the storage unit; and the control unit stores the terminal identification information in the storage unit when the terminal preamble data received from the communication terminal corresponds to the main preamble data or the sub preamble data stored in the storage unit. Access point.

4. An access point that communicates with a communication control device and a communication terminal, a storage unit that stores primary preamble data assigned to the access point and secondary preamble data assigned to other access points; a terminal side transmitting unit that transmits the main preamble data to the communication terminal; a terminal side receiving unit that receives terminal preamble data and terminal identification information for identifying the communication terminal from the communication terminal; a control unit that controls a network-side transmitting unit to transmit the terminal identification information to the communication control device when the terminal preamble data corresponds to either the main preamble data or the secondary preamble data stored in the storage unit; and the control unit controls the terminal-side receiving unit to receive data transmitted and received while another access point is executing a process of establishing a communication link with the communication terminal, when the terminal preamble data received from the communication terminal corresponds to the sub-preamble data stored in the storage unit. Access point.

5. An access point that communicates with a communication control device and a communication terminal, a storage unit that stores primary preamble data assigned to the access point and secondary preamble data assigned to other access points; a terminal side transmitting unit that transmits the main preamble data to the communication terminal; a terminal side receiving unit that receives terminal preamble data and terminal identification information for identifying the communication terminal from the communication terminal; a control unit that controls a network-side transmitting unit to transmit the terminal identification information to the communication control device when the terminal preamble data corresponds to either the main preamble data or the secondary preamble data stored in the storage unit; a network-side receiving unit that receives, after the network-side transmitting unit transmits the terminal identification information to the communication control device, scheduling information that specifies a timing and a frequency for transmitting data to the communication terminal from the communication control device; and the control unit controls the terminal-side transmitting unit to transmit data to the communication terminal based on the scheduling information. Access point.

6. a communication control device, a plurality of access points, and a communication terminal that communicates with the plurality of access points; Each of the plurality of access points a storage unit that stores primary preamble data assigned to the access point and secondary preamble data assigned to other access points; a terminal side transmitting unit that transmits the main preamble data to the communication terminal; a terminal side receiving unit that receives terminal preamble data and terminal identification information for identifying the communication terminal from the communication terminal; a control unit that controls a network-side transmitting unit to transmit the terminal identification information to the communication control device when the terminal preamble data corresponds to either the main preamble data or the secondary preamble data stored in the storage unit; and The communication terminal a terminal receiving unit that receives the plurality of main preamble data transmitted from the plurality of access points; a terminal transmitting unit that transmits the terminal preamble data corresponding to any one of the plurality of main preamble data received by the terminal receiving unit; and The communication control device an information creating unit that creates scheduling information for the plurality of access points to perform data communication with the communication terminal in response to receiving the terminal identification information from the network side transmitting unit of each of the plurality of access points; an information transmitting unit that transmits the scheduling information to the plurality of access points; having Wireless communication system.

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