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JP-7856155-B2 - Control method, control device, wireless communication system, and program

JP7856155B2JP 7856155 B2JP7856155 B2JP 7856155B2JP-7856155-B2

Inventors

  • 岩本 真尚
  • 鈴木 晃人
  • 小林 正裕

Assignees

  • ＮＴＴ株式会社

Dates

Publication Date
20260511
Application Date
20220804

Claims (7)

  1. A control method performed by a control device that determines the tilt of a rescue antenna for rescuing communications in a faulty area, A rescue antenna selection step involves obtaining an antenna sequence in which multiple antennas are arranged in descending order of priority using a policy function, and selecting antennas as rescue antennas in order from the beginning of the antenna sequence until a predetermined condition is met. The system includes a tilt calculation step that calculates the tilt of each rescue antenna selected in the rescue antenna selection step, The aforementioned policy function has parameters pre-trained using rewards based on improving coverage of the faulty area and suppressing overlap in coverage areas between rescue antennas. Control method.
  2. In the pre-training step in which the policy function is pre-trained using training data, the control device: The control method according to claim 1, wherein the policy function obtains an antenna sequence in which multiple antennas are arranged in descending order of priority, and until a predetermined condition is met, antennas are selected as rescue antennas in order from the beginning of the antenna sequence, and the parameters of the policy function are updated based on the reward obtained when all selected rescue antennas are used.
  3. The control method according to claim 1, wherein the predetermined condition is that the coverage rate of the fault area becomes 100%, or that all antennas are selected from the antenna row.
  4. The control method according to any one of claims 1 to 3, wherein the policy function takes the height of the antenna, the distance between the antenna and the centroid of the faulted area, and the difference in azimuth angle between the center azimuth of the antenna and the azimuth from the antenna to the centroid as inputs for each antenna in the set of antennas that are candidates for rescue antennas, and outputs the antenna array.
  5. A control device for determining the tilt of a rescue antenna that rescues communications in a faulty area, A rescue antenna selection unit obtains an antenna sequence in which multiple antennas are arranged in descending order of priority using a policy function, and selects antennas as rescue antennas in order from the beginning of the antenna sequence until predetermined conditions are met. The system includes a tilt calculation unit that calculates the tilt of each rescue antenna selected by the rescue antenna selection unit, The aforementioned policy function has parameters pre-trained using rewards based on improving coverage of the faulty area and suppressing overlap in coverage areas between rescue antennas. Control device.
  6. A wireless communication system comprising a rescue antenna for restoring communications in a faulty area, a control device for determining the tilt of the rescue antenna, and one or more wireless base stations, The control device is A rescue antenna selection unit obtains an antenna sequence in which multiple antennas are arranged in descending order of priority using a policy function, and selects antennas as rescue antennas in order from the beginning of the antenna sequence until predetermined conditions are met. The system includes a tilt calculation unit that calculates the tilt of each rescue antenna selected by the rescue antenna selection unit, The aforementioned policy function has parameters pre-trained using rewards based on improving coverage of the faulty area and suppressing overlap in coverage areas between rescue antennas. Wireless communication system.
  7. A program for causing a computer to function as a component of the control device described in claim 5.

Description

This invention relates to a technology for recovering areas in a mobile communication network that have become unusable due to a failure of a wireless base station. When a wireless base station malfunctions due to a natural disaster or other cause, communication disruptions occur in the area it covered. Because wireless communication requires high availability, restoration within a short timeframe of a few minutes is essential. In contrast, there is a technology that restores service from a failure by changing the tilt angle of the base station antennas surrounding the affected area to cover (relieve) the affected area. This technology is called Cell Outage Compensation (COC). W. Li et al., "Automated cell outage compensation mechanism based on downtilt adjustments in cellular networks," in ISCIT, 2016, pp. 1-6.M. Yin et al., "Cell outage compensation based on CoMP and optimization of tilt," J. China Univ. Posts Telecommun., vol. 22, no. 5, pp. 71-79, 2015. This is a diagram showing the system configuration in an embodiment of the present invention.This is a diagram illustrating the configuration of a wireless base station control device.This is a diagram showing d max and d min .This diagram shows two sectors.This is a flowchart illustrating the operation of a wireless base station control device.This is a flowchart illustrating the operation of a wireless base station control device.This figure shows an example of the device's hardware configuration. Hereinafter, embodiments of the present invention (this embodiment) will be described with reference to the drawings. The embodiments described below are merely examples, and the embodiments to which the present invention is applied are not limited to the embodiments described below. (Definition of terms) First, we will explain the definitions of "antenna" and "regional mesh" as used in this specification. (1) Antennas A base station consists of multiple antennas, each responsible for communication coverage in a specific direction. At this time, a tilt is set for each antenna, and different tilts result in different coverage areas. Since there are cases where only some of the base station's antennas fail, this embodiment considers antenna-level failures rather than base station-level failures. (2) Regional Mesh A regional mesh is defined by the Administrative Management Agency (now the Ministry of Internal Affairs and Communications) as "an area divided into meshes of approximately the same size based on latitude and longitude." In this embodiment, a regional mesh is referred to as a mesh. In this embodiment, all areas, including fault areas and areas covered by rescue antennas, are considered in terms of mesh units. There are multiple patterns for the area per mesh, and a larger area indicates a coarser mesh size. Examples include standard mesh (side length approximately 1 km), half mesh (side length approximately 500 m), and 1/8 mesh (side length approximately 125 m). The coarser the mesh granularity, the less computation is required to calculate the coverage area, thus reducing the time required for coverage area estimation. The mesh granularity can be predetermined, for example, by the operator of the wireless base station control device 100 in this embodiment. (Regarding the challenges) Here, we will describe in detail the prior art and its problems with respect to the technology of this embodiment. In the following description, the contents disclosed in Non-Patent Documents 1 and 2 are publicly known, but the description of their problems is not publicly known. First, I will explain the COC, which forms the basis of the technology disclosed in Non-Patent Documents 1 and 2. The COC consists of the following two steps. <Rescue Antenna Selection Steps> First, an antenna to be used for rescue is selected from among the antennas available around the faulty area. This step is called the rescue antenna selection step, and the selected antenna is called the rescue antenna. In the rescue antenna selection step, an algorithm is used to select an antenna that is most likely to cover the faulty area. <Tilt Optimization Steps> Next, the tilt of the rescue antennas is optimized. This step is called the tilt optimization step. In the tilt optimization step, the tilt of the rescue antennas is controlled so that a high coverage rate is obtained for the faulted area and the overlap of the coverage areas of the rescue antennas is minimized. (1) Conventional technology and its problems 1 Non-patent document 1 proposes a COC (Control-Oriented Convergence) method aimed at maximizing the number of user connections in a faulty area. In this method, all antennas adjacent to the faulty area are selected as rescue antennas. As a result, the number of rescue antennas becomes excessive, and the solution space to be searched when optimizing the tilt of the rescue antennas becomes large. As a result, the accuracy of the optimized solution may decrease, potentially leading to overlapp