A control device that selectively uses multiple antennas, a terminal device that communicates with the control device, a communication method, and a computer-readable storage medium.

Abstract

A control device that communicates wirelessly with a terminal device, when receiving a random access preamble from the terminal device, if the random access preamble is not based on a setting notified by the control device, scrambles the communication between the control device and the terminal device after receiving the random access preamble using a scrambling sequence based on second identification information, wherein the second identification information is different from the first identification information corresponding to the control device.

Description

Technical Field

[0001] This invention relates to a control device, a terminal device, a communication method, and a computer-readable storage medium, and more specifically to a connection control technology in wireless communication. Background Technology

[0002] A technique is currently being researched in which multiple antennas are arranged at high density, and a portion of these antennas is used to perform communication with a terminal device. In this technique, a cell is virtually configured for each terminal device by using different antennas, with the terminal device positioned approximately in the center of the virtual cell (see Non-Patent Document 1). According to this technique, the terminal device can achieve consistent communication quality regardless of its location.

[0003] Existing technical documents

[0004] Non-patent literature

[0005] Non-patent literature

[0006] Non-patent document 1: M.Karlsson etc., "Techniques for System InformationBroadcast in Cell-Free Massive MIMO", IEEE Transaction on Communication, January 2019 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] In the aforementioned system where antennas are arranged in a high density and at least some of them are selectively used, the process by which the terminal device establishes a connection with the base station device for communication has not yet been determined. Therefore, it is necessary to define a process for efficiently establishing a connection between the base station device and the terminal device.

[0009] Means used to solve problems

[0010] This invention provides a technique for efficiently establishing a connection between a base station device and a terminal device in a system, wherein a portion of a plurality of antennas are selected for communication between the base station device and the terminal device.

[0011] According to one aspect of the invention, a control device is a control device that communicates wirelessly with a terminal device, having a control unit that, when receiving a message corresponding to a random access preamble from the terminal device, if the message is not based on a setting notified to the terminal device by the control device, scrambles the communication with the terminal device after receiving the random access preamble using a scrambling sequence based on second identification information, the second identification information being different from first identification information corresponding to the control device.

[0012] According to another aspect of the present invention, a terminal device has a communication unit that includes identification information for a control device receiving the message to determine a scrambling sequence to be used when scrambling communication with the terminal device, in a message corresponding to a random access preamble, sends the message, and after sending the message, performs communication with the control device that has been scrambled using the scrambling sequence.

[0013] Invention Effects

[0014] According to the present invention, a connection can be efficiently established between a base station device and a terminal device in a system in which a portion of a plurality of antennas are selected for communication between the base station device and the terminal device.

[0015] Other features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings. It should be noted that, in the drawings, the same or identical structures are labeled with the same reference numerals. Attached Figure Description

[0016] The accompanying drawings, which are included in and form a part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.

[0017] Figure 1 This is a diagram illustrating an example of the structure of a wireless communication system.

[0018] Figure 2 This is a diagram illustrating an example of the hardware configuration of a control device and a terminal device.

[0019] Figure 3 This is a diagram illustrating an example of the functional configuration of a control device.

[0020] Figure 4 This is a diagram illustrating an example of the functional configuration of a terminal device.

[0021] Figure 5 This is a diagram illustrating an example of a process executed in a wireless communication system.

[0022] Figure 6 This is a diagram illustrating an example of a process executed in a wireless communication system.

[0023] Figure 7 This is a diagram illustrating an example of a process executed in a wireless communication system. Detailed Implementation

[0024] The embodiments will now be described in detail with reference to the accompanying drawings. It should be noted that the following embodiments do not limit the invention as defined in the claims. Multiple features are described in the embodiments, but not all of these features are limited to those essential to the invention; furthermore, multiple features can be arbitrarily combined. Furthermore, in the accompanying drawings, the same or identical structures are labeled with the same reference numerals, and repeated descriptions are omitted.

[0025] (System Configuration)

[0026] Figure 1 An example configuration of a wireless communication system according to this embodiment is shown. For example... Figure 1 As shown, in the wireless communication system according to this embodiment, multiple antennas are arranged in a high-density plane, and these antennas are connected to a control device 101, such as a base station device, via, for example, optical fiber. The control device 101 is connected to and communicates with a terminal device 102 via at least one antenna. It should be noted that, for the sake of simplicity, Figure 1 Only a few control devices 101 and one terminal device 102 are shown in the diagram; of course, these devices may also exist in a larger number of ways. Figure 1 The situation shown is multifaceted.

[0027] It should be noted that the following description assumes that the antennas are arranged in a distributed manner and connected to the control device. However, only antennas can be arranged in a high density, or antenna elements with RF processing capabilities, such as radio frequency (RF) filters, can be arranged in a high density. The control device 101 performs communication processing in addition to the processing performed on the antenna side. That is, the control device 101 performs baseband processing of the received signal and subsequent signal processing at higher layers. Figure 1 As shown, when constructing a system using a large number of antennas, considering computational load, it is envisioned that multiple control devices 101 are connected to multiple antennas respectively for signal transmission and reception. It should be noted that the system can be configured to use a known centralized radio access network (C-RAN), where each antenna can correspond to a transmit / receive point (TRP) of the C-RAN, and the control device 101 can correspond to a baseband unit (BBU) of the C-RAN.

[0028] Terminal device 102 is connected to and communicates with control device 101 via an antenna located nearby. Using at least a portion of the antennas connected to control device 101, control device 101 communicates with terminal device 102 while a connection has already been established. Here, two or more control devices 101 can establish connections with terminal device 102 and communicate in parallel. Therefore, one or more control devices 101 can configure a virtual area (also called a user center area) centered on terminal device 102, and can provide high-quality, highly stable communication services regardless of the location of terminal device 102.

[0029] In contrast, no research has been conducted on the processing performed when establishing a connection in such a system using multiple antennas. In existing cellular wireless communication systems such as LTE, scrambling inherent to the cell corresponding to the cell identification information (cell ID) is applied to the reference signal sequence or user data. Therefore, inter-cell interference is randomized, and communication quality can be improved. Furthermore, in existing cellular wireless communication systems, terminal-inherent scrambling can also be applied to the reference signal sequence or user data. Due to this terminal-inherent scrambling, interference is randomized when different cells corresponding to different cell IDs conduct cooperative communication, enabling simultaneous transmission in cooperative communication. On the other hand, when existing technologies are applied to systems such as… Figure 1 The system shown envisions that during the random access process (hereinafter referred to as "RACH" or "RACH processing") for establishing a connection, after applying the cell-specific scrambling and establishing a connection, the terminal-specific scrambling is set in the terminal device as needed, and then communication is performed using the terminal-specific scrambling. However, since two or more control devices 101 correspond to different cell IDs, when the terminal device 102 performs RACH processing, it only uses the antenna connected to the control device 101, and the terminal device attempts to establish a connection with the control device through the RACH processing. Therefore, the communication quality of the RACH processing performed by the terminal device 102 using multiple antennas cannot be sufficiently improved, and the possibility of RACH processing failure increases. Furthermore, after the terminal device 102 performs RACH processing and subsequently connects to a predetermined control device 101, high-quality communication for the terminal device 102 can only be provided until the scrambling sequence inherent to the terminal device 102 is shared by two or more control devices 101 communicating with the terminal device 102. In view of this situation, this embodiment provides a technique for optimizing the method used when the terminal device 102 establishes an initial connection with one or more control devices 101.

[0030] In this embodiment, the first control device determines whether the random access preamble received from the terminal device 102 (e.g., included in message A of a two-step RACH, or as message 1 of a four-step RACH) is based on a setting that the first control device itself notifies the terminal device of. If the random access preamble is based on a setting of the first control device, then thereafter, the first control device uses a first scrambling sequence corresponding to a first cell ID for communication. On the other hand, if the random access preamble is not based on a setting that the first control device itself notifies the terminal device of, then in subsequent communication, the first control device does not use the first scrambling sequence corresponding to the first cell ID, but instead uses a second scrambling sequence corresponding to a second cell ID.

[0031] The second cell ID can be, for example, the cell ID of a second control device that is adjacent to the first control device. Therefore, the first control device can communicate with the terminal device 102 that sends the random access preamble to the second control device using a scrambling sequence corresponding to the cell ID of the second control device. Thus, the first and second control devices can cooperate to perform processing after sending the response message for the random access preamble, improving the reliability of the RACH process. Furthermore, since the scrambling sequence corresponding to the second cell ID is also used after the RACH process, there is no need to set a new scrambling sequence inherent to the terminal device 102. Therefore, high-quality wireless communication services can be provided to the terminal device 102 after the connection is established.

[0032] It should be noted that, for example, the first control device can obtain information about the cell ID from control devices with pre-defined proximity relationships and retain this information. Furthermore, a configuration can be adopted such as: when a random access preamble is received, if the random access preamble is not based on a setting notified to the terminal device by the first control device, the first control device sends the random access preamble to a second control device with which it has a proximity relationship, queries the cell ID, and obtains the second cell ID. For example, if the received random access preamble is based on a setting notified to the terminal device by the second control device, the second control device can notify its own second cell ID. It should be noted that a configuration can be adopted such that the control device retains information about cell IDs associated with more than one second control device in advance and obtains a response by sending a random access preamble, the response being only related to whether the random access preamble is based on a setting notified to the terminal device by the queried second control device. In this case, if the received random access preamble is based on a setting notified to the terminal device by a control device (which received the query), the control device receiving the query can notify "ACK" to the querying control device as a response; otherwise, it notifies "NACK". It should be noted that, in addition to ACK / NACK, a small amount of information, such as one bit, can be sent / received. This small amount of information indicates whether the random access preamble is based on a setting notified to the terminal device by the control device that the query was received. Furthermore, the first control device can, for each of more than one second control device, store the cell ID and a seed, such as the sequence used to generate the random access preamble (information that determines the random access preamble), in association. In this case, for example, by using a sequence based on a seed associated with the first control device itself and a sequence based on a seed associated with the second control device for correlation detection, the first control device determines which control device the received random access preamble is associated with. When it is detected that the random access preamble is based on a seed associated with a device other than the first control device, the first control device determines that the cell ID is stored in association with that seed, and in subsequent communications, a scrambling sequence corresponding to that determined cell ID is used.

[0033] In addition to the random access preamble, the terminal device 102 can also transmit a virtual cell ID in the Physical Uplink Shared Channel (PUSCH) sent in message A of the two-step RACH. In this case, regardless of whether the destination of the random access preamble is the first control device itself, the first control device can use the virtual cell ID as the aforementioned second cell ID. Therefore, from the time message B is sent after receiving message A, the control device that received message A will use the scrambling sequence based on the virtual cell ID as its inherent scrambling sequence, and multiple control devices can cooperate to send signals. It should be noted that the information notified by the terminal device only needs to be information that can determine the scrambling sequence, and does not need to be the virtual cell ID.

[0034] As described above, in this embodiment, starting from the response to the random access preamble transmission of the RACH process, multiple control devices can use a shared scrambling sequence, thereby improving the wireless quality during the RACH process and providing a high-quality communication environment for the terminal device immediately after the connection is established.

[0035] (Device Configuration)

[0036] The configuration of the control device that performs the above processing will be described next. It should be noted that the terminal device may have a similar configuration. Figure 2 An example of the hardware configuration of a control device is shown. In one example, the control device includes a processor 201, a ROM 202, a RAM 203, a storage device 204, and a communication circuit 205. In the control device, the processor 201 executes a computer-readable program recorded in, for example, any one of the ROM 202, RAM 203, and storage device 204 for implementing the functions of the control device. It should be noted that the processor 201 can be replaced by more than one processor, for example, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), and a digital signal processor (DSP).

[0037] The control device communicates with the peer device (e.g., a terminal device, other control devices, upper-level nodes, etc.) via, for example, processor 201 controlling communication circuit 205. It should be noted that... Figure 2 A schematic diagram of a control device having a communication circuit 205 is shown; however, this is not a limitation. For example, the control device may have a communication device for communicating with a terminal device, and a communication device for communicating with other control devices or upper-level nodes.

[0038] Figure 3An example of the functional configuration of the control device is shown. The control device, for example, includes a communication control unit 301, a scrambling sequence setting unit 302, an information acquisition unit 303, and an information notification unit 304. The communication control unit 301 controls communication with the terminal device. The communication control unit 301 receives a random access preamble from the terminal device and, for example, sends a random access response in response to it (e.g., included in message B of a two-step RACH, or as message 2 of a four-step RACH), thereby establishing a connection with the terminal device.

[0039] The scrambling sequence setting unit 302 sets the scrambling sequence to be used. For example, if the random access preamble is not based on a setting notified to the terminal device by the control device, the scrambling sequence setting unit 302 of the control device sets the communication control unit 301 to use a scrambling sequence based on a second cell ID different from the first cell ID of the control device. The second cell ID can be, for example, the cell ID of another control device that has a neighboring relationship. It should be noted that if the PUSCH included in message A from the terminal device contains a virtual cell ID, the scrambling sequence setting unit 302 sets the communication control unit 301 to use a scrambling sequence based on the virtual cell ID. It should be noted that if such a virtual cell ID is notified, the scrambling sequence setting unit 302 can set the settings of the communication control unit 301 to use a scrambling sequence based on the virtual cell ID, regardless of whether the random access preamble is based on a setting notified to the terminal device by the control device. On the other hand, if the virtual cell ID is not notified and the random access preamble is not based on the settings notified to the terminal device by the control device, the scrambling sequence setting unit 302 of the control device sets the communication control unit 301 so as to use a scrambling sequence based on the cell ID of the control device.

[0040] Information acquisition unit 303 acquires the aforementioned second cell ID. A query containing a random access preamble is sent to, for example, another control device with a proximity relationship. Information acquisition unit 303 then determines, by receiving a response to the query, whether the received random access preamble is based on a setting notified to the terminal device by the other control device. If the received random access preamble is based on a setting notified to the terminal device by the other control device, information acquisition unit 303 uses the cell ID of the other control device as the second cell ID. It should be noted that information acquisition unit 303 can acquire information from other control devices, which only indicates whether the received random access preamble is based on a setting notified to the terminal device by the other control device, or can acquire the cell ID of the other control device itself. When another control device submits a similar query, information notification unit 304 notifies the other control device that made the query of the cell ID and information indicating whether the random access preamble included in the query is based on a setting notified to the terminal device by the control device (which received the query). It should be noted that, for example, the following configuration may be adopted: the information acquisition unit 303 stores the seed and cell ID of the random access preamble in association, determines which seed the received random access preamble corresponds to, and determines the cell ID associated with the determined seed as the second cell ID.

[0041] Figure 4 An example of the functional configuration of a terminal device is shown, which adds a virtual cell ID to message A in a two-step RACH and sends message A. The terminal device has, for example, a communication processing unit 401 and a cell ID notification unit 402. The communication processing unit 401 establishes a connection with a control device and performs wireless communication. The cell ID notification unit 402 sends message A, in which the virtual cell ID is included in the PUSCH portion, to a nearby control device. It should be noted that the virtual cell ID is exemplary, and any information that can determine the scrambling sequence inherent to the terminal device can be notified to the control device.

[0042] (Processing flow)

[0043] The following will describe some examples of the processing flow to be performed in the wireless communication system according to this embodiment. It should be noted that detailed descriptions of the above operations may be omitted. It should also be noted that the detailed descriptions above will not be repeated here; only the processing flow will be illustrated schematically.

[0044] Figure 5A first example of the processing flow is shown. First, each control device sends a notification message containing parameters for sending a random access preamble for itself (S501, S502). It should be noted that these parameters include information about the seed used to generate the random access preamble sequence, information about the time / frequency resources for which the random access preamble should be sent, etc. Subsequently, the terminal device sends a random access preamble (e.g., included in a two-step RACH message A, or as a four-step RACH message 1) to control device A, for example, based on notification message A received from control device A (S503). Control device A receives the random access preamble based on notification message A provided by control device A itself, and thereafter, control device A uses this scrambling sequence based on its cell ID (cell ID-A) to scramble its communication with the terminal device (S506). On the other hand, control device B receives a random access preamble based on notification information A, which is different from the notification information B provided by control device B itself. Control device B then attempts to obtain the cell ID, for example, by querying other control devices with neighboring relationships that include the random access preamble (S504). Control device B then receives the cell ID (cell ID-A) of control device A from control device A that sent the notification information A used to generate the random access preamble (S505). It should be noted that control device B can also perform similar queries to other control devices, but these other control devices do not correspond to the random access preamble based on their notification information and therefore do not notify the cell ID (not shown). After this, control device B scrambles its communication with the terminal device using a scrambling sequence based on the cell ID (cell ID-A) obtained in S505 (S506). In this technique, changes in the neighboring relationships between control devices can be flexibly handled by querying the cell ID each time.

[0045] It should be noted that each control device can store information therein, including interrelated information about the random access preamble and the cell ID, and the cell ID can be determined based on the received random access preamble. Figure 6 An example of the processing flow in this scenario is shown. Figure 6 In the middle, control device B performs the operation of determining the cell ID corresponding to the received random access preamble based on the information stored therein (S601), but does not perform... Figure 5 S504 and S505 in the example. Using this technology, no query is required, thus reducing processing time.

[0046] Alternatively, the following configuration can be used: the terminal device adds the virtual cell ID used to generate the scrambling sequence to message A of the two-step RACH and sends the message, while the control device uses the scrambling sequence based on the virtual cell ID for communication. Figure 7 An example of the processing flow is shown. Figure 7 In this process, the terminal device sends message A, which includes a random access preamble based on notification information provided by the control device A and a PUSCH containing cell ID-C as the virtual cell ID (S701). The control device A then detects the random access preamble based on the parameters it sent in notification information A and obtains cell ID-C from the next PUSCH. Furthermore, for example, as... Figure 6 As shown, control device B obtains information such as a seed in advance, which is used to generate a random access preamble sequence used by other control devices with adjacent relationships, thereby obtaining information similar to the information notified using notification information A. Similar to control device A, control device B then detects the random access preamble and obtains the cell ID-C from the next PUSCH. Control device A and control device B then communicate using a scrambling sequence based on the notified cell ID-C (S702).

[0047] Based on the processing example described above, multiple control devices can use a shared scrambling sequence derived from the response to the random access preamble transmission in the RACH process. Therefore, the radio quality during RACH processing can be improved, and a high-quality communication environment can be provided to the terminal device immediately after connection establishment.

[0048] This invention is not limited to the above-described embodiments. Various changes and modifications can be made without departing from the spirit and scope of this invention.

Claims

1. A control device that communicates wirelessly with a terminal device, wherein, The control device has: A control unit is configured to, in the case that each notification from the control device and other control devices contains information about the setting of a random access preamble, and when the control device receives the random access preamble from the terminal device, if the random access preamble is not based on the setting notified by the control device, scramble the communication with the terminal device after receiving the random access preamble using a scrambling sequence based on second identification information, which is different from first identification information corresponding to the control device.

2. The control device according to claim 1, wherein, The control unit is configured to use the identification information notified in the message containing the random access preamble from the terminal device as the second identification information.

3. The control device according to claim 2, wherein, The message is message A in a two-step random access process, and the control device receives from the terminal device a notification of identification information that should be used as the second identification information in the physical uplink shared channel portion of message A.

4. The control device according to claim 2 or 3, wherein, When the control device receives notification of the identification information in the message from the terminal device, even if the random access preamble is based on a setting notified by the control device, the control unit is configured to scramble communication with the terminal device after receiving the random access preamble using a scrambling sequence based on the second identification information.

5. The control device according to claim 1, wherein, When the random access preamble is based on a setting notified by the other control device, the control unit is configured to use the identification information corresponding to the other control device as the second identification information.

6. The control device according to claim 5, wherein, The control device further includes an acquisition unit configured to send a query containing the random access preamble to the other control device and acquire the second identification information.

7. The control device according to claim 1, wherein, The control device also has a notification unit configured to notify the other control device, when the control device receives a query containing a random access preamble from the other control device, whether the random access preamble is based on a setting notified by the control device.

8. The control device according to claim 1, wherein, The control device further includes a storage unit configured to store, in association with each of one or more other control devices, information that can determine a set random access preamble based on notification from that other control device, and identification information corresponding to that other control device. The control unit is configured to determine which of the more than one other control devices the received random access preamble is based on, and to use the identification information corresponding to the determined device as the second identification information.

9. A terminal device, wherein, The terminal device has a communication unit configured to receive information from each of a first control device and a second control device, including information about the setting of a random access preamble, wherein the message containing the random access preamble includes second identification information, which is different from first identification information corresponding to the control device and is used to enable the first and second control devices receiving the message to determine a scrambling sequence to be used when scrambling communication with the terminal device, to send the message, and after sending the message, to conduct communication with the first and second control devices scrambled using the scrambling sequence determined by the second identification information.

10. The terminal device according to claim 9, wherein, The message is message A in the two-step random access process, and the communication unit notifies the second identification information in the physical uplink shared channel portion of message A.

11. A communication method performed by a control device communicating wirelessly with a terminal device, wherein, The communication method includes: In cases where each notification in the control device and other control devices contains information about the setting of a random access preamble, and when the random access preamble is received from the terminal device, if the random access preamble is not based on the setting notified by the control device, the communication between the terminal device and the terminal device after receiving the random access preamble is scrambled using a scrambling sequence based on second identification information, which is different from the first identification information corresponding to the control device.

12. A communication method executed by a terminal device, wherein, The communication method includes: Receive information from each of the first and second control devices, including settings for the random access preamble. The message containing the random access preamble includes second identification information, which is different from the first identification information corresponding to the control device and is used by the first and second control devices receiving the message to determine the scrambling sequence to be used when scrambling communication with the terminal device. The message is sent, and after the message is sent, communication is conducted between the first control device and the second control device using the scrambling sequence determined by the second identification information.

13. A computer-readable storage medium storing a program, wherein, The program is used to enable a computer in a control device that communicates wirelessly with a terminal device to perform the following operations: In cases where each notification in the control device and other control devices contains information about the setting of a random access preamble, and when the control device receives the random access preamble from the terminal device, if the random access preamble is not based on the setting notified by the control device, the communication between the control device and the terminal device after receiving the random access preamble is scrambled using a scrambling sequence based on second identification information, which is different from the first identification information corresponding to the control device.

14. A computer-readable storage medium storing a program, wherein, The program is used to enable the computer in the terminal device to perform the following operations: Receive information from each of the first and second control devices, including settings for the random access preamble. The message containing the random access preamble includes second identification information, which is different from the first identification information corresponding to the control device and is used by the first and second control devices receiving the message to determine the scrambling sequence to be used when scrambling communication with the terminal device. The message is sent, and after the message is sent, communication is conducted between the first control device and the second control device using the scrambling sequence determined by the second identification information.

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