Base station and communication terminal

Abstract

A base station 3 in a communication system in which communication is performed via a relay device 2 between the base station 3 and a communication terminal 1 receives information pertaining to a schedule for performing beam control between the communication terminal 1 and the relay device 2 from the communication terminal 1 (S2) and, when the communication terminal 1 performs beam control in the schedule, notifies the communication terminal 1 regarding control information for preventing allocation of a resource to the communication terminal 1 (S3, S4).

Description

Base station and communication terminal

[0001] The present invention relates to a base station and a communication terminal in a communication system in which a relay device also performs beam control.

[0002] Non-Patent Documents 1 and 2, etc., of the prior art, propose a communication system that performs communication between a base station (BS) and a user equipment (UE) using dynamic beamforming, in which, to select an optimal combination from multiple beam patterns, the UE switches the beam pattern within a beam selection period (beam sweeping period), selects one or more from the observation results of synchronization signals (PSS / SSS) and reference signals (CSI-RS) transmitted by each beam pattern of the BS, and feeds these observation results together with the observation results (RSRP / RSRQ) back to the BS. Based on the feedback, the BS determines the beam to use for communication with the UE, and communicates with the UE using the determined beam.

[0003] 3GPP (registered trademark) TR38.802, V14.1.0: "Study on new radio access technology physical layer aspects (Release 14)," June 2017. 3GPP (registered trademark), TS 38.214, "NR Physical layer procedures for data," v16.6.0, June 2021.

[0004] On the other hand, wireless relay devices, also known as radio frequency repeaters (RF repeaters), are being used to expand the area coverage of BSs and improve the communication environment for UEs located in dead spots within the area coverage. Conventional technologies that do not consider how to handle RF repeaters when performing dynamic beamforming on relay devices have the problem of wasting resources allocated by BSs to UEs.

[0005] Figure 1 is a diagram illustrating a problem with the related art. In step a, a base station (BS) performs beam sweeping, i.e., transmission by sequentially switching between multiple beam patterns that indicate the directionality of electromagnetic wave transmission and reception. A communication terminal (UE) evaluates the communication quality of the multiple beam patterns by measuring the beams via a relay device (Rep). Based on the evaluation results, the base station determines the beam pattern to be used for communication with the communication terminal via the relay device. Based on this determination, in step b, the base station allocates a PDCCH (Physical Downlink Control Channel). In accordance with this allocation, the base station transmits downlink data via a PDSCH (Physical Downlink Shared Channel) as in step c.

[0006] However, in a configuration in which the relay device also performs beam sweeping, it is necessary to appropriately re-establish the access link between the communication terminal and the relay device (access link) by having the communication terminal perform beam sweeping (and beam measurement) periodically or in an event-driven manner triggered by the detection of a link disconnection, as in step d. During step d when the beam sweeping is being performed, the link between the communication terminal and the relay device is not established in the first place, so if steps c and d overlap in time, step c will be wasted, and the resources allocated to the communication terminal in step b will be wasted.

[0007] In view of the problems of the related art, a first object of the present invention is to provide a base station that can prevent resource waste in a communication system in which a relay device also performs beam control, and a second object of the present invention is to provide a communication terminal that can prevent resource waste in a communication system in which a relay device also performs beam control.

[0008] In order to achieve the first object, the present invention has a first feature in that a base station in a communication system in which communication is performed between a base station and a communication terminal via a relay device receives information from the communication terminal regarding a schedule for performing beam control between the communication terminal and the relay device, and when the communication terminal is performing beam control on the schedule, notifies the communication terminal of control information that prevents resources from being allocated to the communication terminal.

[0009] In addition, in order to achieve the second object, the present invention has a second feature in that a communication terminal in a communication system in which communication is performed between a base station and a communication terminal via a relay device notifies the base station of information on a schedule for performing beam control between the communication terminal and the relay device, and receives control information notified by the base station that prevents resources from being allocated to the communication terminal when the communication terminal is performing beam control.

[0010] According to the first or second feature, by using information on a schedule for performing beam control between a communication terminal and a relay device, when the communication terminal is performing beam control in that schedule, resources are not allocated to the communication terminal, and those resources are made available for resource allocation to other communication terminals, thereby preventing waste of resources.

[0011] Other features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which the same or similar elements are designated by the same reference numerals.

[0012] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present invention. A diagram schematically illustrating a problem in the prior art. A diagram illustrating the configuration of a communication system according to an embodiment. A diagram illustrating an operation sequence of a communication system according to an embodiment.

[0013] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention as claimed, and not all combinations of features described in the embodiments are necessarily essential to the invention. Two or more of the features described in the embodiments may be combined in any desired manner. Furthermore, the same reference numerals are used to designate identical or similar components, and redundant descriptions will be omitted.

[0014] 2 is a configuration diagram of a communication system 100 according to one embodiment. The communication system 100 includes a communication terminal (UE) 1, a relay device (Rep) 2, and a base station (BS) 3. The communication terminal 1 includes a UE communication unit 11 and a UE control unit 12. The relay device 2 includes a UE side communication unit 21, a BS side communication unit 22, and a Rep control unit 23. The base station 3 includes a BS communication unit 31 and a BS control unit 32.

[0015] The UE control unit 12, Rep control unit 23, and BS control unit 32 can all be configured with a processor such as a CPU, RAM, ROM, etc., and can perform control processing by executing predetermined programs and store information required for the control processing. The UE control unit 12 controls communication by the UE communication unit 11, the Rep control unit 23 controls communication by the UE side communication unit 21 and the BS side communication unit 22, and the BS control unit 32 controls communication by the BS communication unit 31.

[0016] The communication terminal 1 and the relay device 2 communicate over an access link through wireless communication between the UE communication unit 11 and the UE side communication unit 21, and the relay device 2 and the base station 3 communicate over a backhaul link through wireless communication between the BS side communication unit 22 and the BS communication unit 31. The UE communication unit 11, the UE side communication unit 21, the BS side communication unit 22, and the BS communication unit 31 can all perform directional communication by switching between multiple beam patterns.

[0017] 3 is a diagram showing an operation sequence of a communication system 100 according to an embodiment. Step S1 is the same as step a described above, in which the base station 3 sweeps beams of multiple beam patterns, and the communication terminal 1 evaluates the communication quality of the multiple beam patterns by measuring the beams via the relay device 2. Based on the evaluation results, the base station 3 determines the beam pattern to be used for communication with the communication terminal 1 via the relay device 2. Step S1 establishes a link between the base station 3 and the relay device 2 and a link between the relay device 2 and the communication terminal 1, enabling communication between the base station 3 and the communication terminal 1 via the relay device 2. This step S1 may be implemented using any existing method. Direct communication between the base station 3 and the communication terminal 1 may occur during the process, or the link establishment may be initiated by the base station 3 or the communication terminal 1.

[0018] In step S2, the communication terminal 1 determines the beam control timing, time width, period, etc. as a schedule for its own access link beam control to re-establish the access link, and then notifies the base station 3 of the schedule via the relay device 2 to request a schedule. The communication terminal 1 may determine the beam control schedule using any method, such as a rule-based method based on its own movement speed or the communication quality with the relay device 2. Alternatively, a predetermined beam control schedule that is set in advance according to the day of the week, region, time period, etc. may be used. Note that with regard to communication between the relay device 2 and the communication terminal 1, the beam from the relay device 2 may be omnidirectional. If there are multiple relay devices 2, the communication terminal 1 may determine the schedule for any one of them (for example, the one with the best communication quality).

[0019] In step S3, base station 3 performs scheduling in accordance with the schedule requested by communication terminal 1 in step S2, thereby allocating resources to communication terminal 1 and other communication terminals (not shown) other than communication terminal 1. That is, the scheduling for allocating RBs (resource blocks that determine which of multiple subcarriers (frequencies) to allocate to which communication terminal at each time (slot)) to be used between communication terminal 1 and other communication terminals is performed assuming that the constraints notified in step S2 are satisfied, by not allocating resources to communication terminal 1 during a time period (slot) when communication terminal 1 is performing beam control with relay device 2, and by allowing resource allocation to communication terminal 1 during a time period when communication terminal 1 is not performing beam control with relay device 2.

[0020] In step S4, the base station 3 notifies the communication terminal 1 via the relay device 2 of the beam control slot scheduled in step S3.

[0021] In step S5, the communication terminal 1 performs beam control in accordance with the notification in step S4. For example, as shown in Fig. 3, if the scheduling content is set so that the time length of the beam control cycle is T3, and beam control is performed during the first half of the time length T1 of the beam control cycle, and the second half of the time length T2 (T1 + T2 = T3) is outside the beam control time, the communication terminal 1 repeatedly performs operations according to the settings in the cycle T3.

[0022] Here, resources can be used effectively on the base station 3 side because scheduling was performed in step S3 in accordance with the beam control schedule of communication terminal 1. That is, during time T1 when communication terminal 1 is performing beam control, no resources are allocated to communication terminal 1, and the unallocated resources are made available for resource allocation to other communication terminals, and during time T2 when communication terminal 1 is outside of beam control, resource allocation to communication terminal 1 is permitted, so resources can be used effectively by preventing unnecessary resource allocation during beam control.

[0023] Various supplementary, alternative, and additional examples of the embodiments of the present invention will be described below. (1) The embodiments of the present invention can contribute to the development of communication infrastructure, thereby contributing to Goal 9 of the United Nations' Sustainable Development Goals (SDGs), "Build resilient infrastructure, promote sustainable industrialization, and foster innovation." (2) In step S2, the communication terminal 1 can use a PRACH (Physical Random Access Channel), a PUCCH (Physical Uplink Control Channel), or an SRS (Sounding Reference Signal) as a method for sending a schedule request to the base station 3. (3) In step S2, the communication terminal 1 can specify beam control timing, the number of slots required for beam control, the beam control period, and other information when sending a schedule request to the base station 3. (4) In step S4, the base station 3 can use a PDCCH (Physical Downlink Control Channel) as a method for notifying the communication terminal 1 of the result of beam control resource allocation.

[0024] The present invention is not limited to the above-described embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present invention.

[0025] This application claims priority based on Japanese Patent Application No. 2023-166201, filed September 27, 2023, the entire contents of which are incorporated herein by reference.

Claims

1. A base station in a communication system in which communication is performed between a base station and a communication terminal via a relay device, the base station receiving schedule information for performing beam control between the communication terminal and the relay device from the communication terminal, and notifying the communication terminal of control information for not allocating resources to the communication terminal when the communication terminal is performing beam control according to the schedule.

2. The base station according to claim 1, characterized in that the control information is notified to the communication terminal using a PDCCH (Physical Downlink Control Channel).

3. The base station according to claim 1 or 2, characterized in that the schedule information includes beam control timing, required number of slots, or period.

4. A base station as claimed in any one of claims 1 to 3, wherein the control information allows allocation of resources to the communication terminal when the communication terminal is not performing beam control in the schedule.

5. A communication terminal in a communication system in which communication is performed between a base station and a communication terminal via a relay device, the communication terminal notifying the base station of schedule information for performing beam control between the communication terminal and the relay device, and receiving control information notified by the base station of the schedule, which prevents resources from being allocated to the communication terminal when the communication terminal is performing beam control.

6. The communication terminal according to claim 5, characterized in that the schedule information is notified to the base station using PRACH (Physical Random Access Channel), PUCCH (Physical Uplink Control Channel) or SRS (Sounding Reference Signal).

7. The communication terminal according to claim 5 or 6, wherein the schedule information includes beam control timing, a required number of slots, or a period.

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