JP5592968B1 - Small base station, radio transmission output adjustment method, and computer program - Google Patents

Abstract

[PROBLEMS] To suppress a decrease in communication service of a small base station due to an increase in communication load.
A small base station is based on one or a combination of two or more of a wireless connection success rate, a location success rate, a voice connection success rate, and a packet connection success rate per unit time. The communication load of the small base station is calculated (step 401). If the communication load exceeds the threshold (step 402; YES), the wireless transmission output of the small base station is lowered so as to reduce the communication load (step 402). 403).
[Selection] Figure 4

Description

  The present invention relates to a technique for reducing the communication load of a small base station.

  In the mobile communication standardization organization 3GPP (Third Generation Partnership Project), a LTE (Long Term Evolution) network using a small base station is considered as a next-generation mobile communication system. A small base station that constitutes one of the nodes of the LTE network is called a HeNB (Home eNode B), and accommodates a mobile device using the same radio access technology as the macro cell base station. The mobile device is, for example, a high-function mobile phone such as a smartphone, and is called UE (User Equipment). The small base station is connected to the core network of the mobile communication system via a broadband line, and relays communication data of mobile devices located in the local station. A small base station uses a broadband line as a backhaul and can be installed by a general user, so it is effective in eliminating radio-insensitive areas such as indoors. In addition, since the cell size of the small base station is smaller than that of the macro cell and accommodates a small number of users, an improvement in throughput per user can be expected as compared with a macro cell base station that accommodates a large number of users.

  However, when a small base station is installed in a busy shop or road, there are cases in which a large number of mobile devices repeat the location / departure range and the number of incoming / outgoing calls may change unexpectedly. obtain. If the communication load suddenly concentrates on the small base station in this way, there is a possibility that the call is disconnected or the communication quality is deteriorated.

  Therefore, an object of the present invention is to suppress a decrease in communication service of a small base station due to an increase in communication load.

In order to solve the above problems, the small base station according to the present invention has one of wireless connection success rate, in-service success rate, voice connection success rate, and packet connection success rate below a threshold per unit time. A calculation means for calculating a communication load based on a frequency or a frequency at which any two or more of each falls below a threshold per unit time; and an adjustment means for dynamically adjusting a wireless transmission output so as to reduce the communication load Prepare. When the communication load increases, the wireless connection success rate, the in-zone success rate, the voice connection success rate, and the packet connection success rate decrease, and the communication load of the small base station can be estimated from these values. A smaller cell size than a larger cell size reduces the number of mobile devices accommodated, and the communication load of the small base station becomes lighter. Therefore, the small base station dynamically adjusts the radio transmission output according to the communication load. As a result, the cell size is adjusted so as to reduce the communication load. Thereby, even when the communication load increases, call disconnection and communication quality degradation can be suppressed, and the quality of the communication service can be maintained.

  ADVANTAGE OF THE INVENTION According to this invention, the fall of the communication service of a small base station by the increase in communication load can be suppressed.

It is a whole block diagram of a mobile communication system provided with the small base station concerning this embodiment. It is a functional block diagram which shows the structure of the small base station concerning this embodiment. It is explanatory drawing which shows the outline | summary of a process of the adjustment method of the radio | wireless transmission output concerning this embodiment. It is a flowchart which shows the flow of a process of the adjustment method of the radio | wireless transmission output concerning this embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is an overall configuration diagram of a mobile communication system 100 including a small base station 10 according to the present embodiment. The small base station 10 is installed in the indoor 31 to provide a wireless access point to the mobile devices 21 and 22 in the indoor 31. The indoor small base station 10 may be called a home base station. When the mobile communication system 100 employs an LTE-based network architecture, the small base station 10 is called a HeNB. In addition, the small base station 10 may be referred to as a small cell base station or a femtocell base station because the cell 30 that is a coverage area where communication radio waves of the small base station 10 reach is smaller than the macro cell. The indoor 31 is inside a building such as an office building, a store, or a house, for example, and is a radio wave insensitive area where radio waves from an outdoor base station are difficult to reach. The small base station 10 is connected to the IP network 40 via a wired line 41 such as an optical fiber or a metal cable. The IP network 40 is connected to the mobile operator's core network 60 via the gateway 50, and transmits data related to voice communication and data communication in packets. In the core network 60, for example, a management server 70 for remotely managing the small base station 10 based on the TR-069 management protocol is arranged. The management server 70 is called an operation support system, for example. Although not shown in FIG. 1, the core network 60 is provided with an exchange for performing call control of the mobile devices 21 and 22, a home location register, a visitor location register, and the like.

  FIG. 2 is a functional block diagram showing the configuration of the small base station 10. The small base station 10 includes an antenna 11 for transmitting and receiving radio waves to and from the mobile devices 21 and 22, an RF processing unit 12 that performs frequency conversion and modulation / demodulation processing of radio signals, and communication protocols and IPs of the mobile devices 21 and 22. A protocol conversion unit 13 that performs protocol conversion with the communication protocol of the network 40, a control unit 14 that controls the operation of the small base station 10 (for example, adjustment of wireless transmission output), and a communication interface that is connected to the IP network 40 15 is provided.

  Next, the outline of the method for adjusting the radio transmission output according to the present embodiment will be described with reference to FIG. The small base station 10 calculates the value of the performance index every certain sampling period (for example, about several tens of minutes to 1 hour), and calculates the communication load based on the frequency at which the value of the performance index falls below a predetermined threshold. To do. The performance index is a parameter called KPI (Key Performance Indicator). Specifically, the wireless connection success rate (RRC Success Rate), the location success rate (Attach Success Rate), and the voice connection success rate (CS Speech Success Rate). ), And a packet connection success rate (PS Speech Success Rate). The small base station 10 dynamically adjusts the wireless transmission output so that the communication load is reduced. For example, when the communication load is heavy, as indicated by reference numeral 30A, the small base station 10 reduces the radio transmission output, thereby reducing the cell size and reducing the number of mobile units accommodated in the cell. On the other hand, when the communication load is light, as indicated by reference numeral 30B, the small base station 10 increases the radio transmission output, thereby increasing the cell size and increasing the number of mobile units accommodated in the cell. In this way, by automatically changing the cell size so as to reduce the communication load, it is possible to suppress call disconnection and communication quality degradation and maintain the quality of communication services. In the figure, for convenience of explanation, the case where the cell size is adjusted in two stages is illustrated, but the cell size may be adjusted in three stages or more according to the communication load.

  FIG. 4 is a flowchart showing a processing flow of the wireless transmission output adjustment method according to the present embodiment. In step 401, the small base station 10 calculates a communication load from the KPI value. The KPI used for calculating the communication load may be any one of a wireless connection success rate, a location success rate, a voice connection success rate, and a packet connection success rate, or a combination of any two or more. A threshold is set for the KPI used for calculating the communication load, and the communication load is calculated based on the frequency at which the KPI value falls below the threshold per unit time. When two or more KPIs are used, the communication load is calculated based on the frequency with which each KPI value falls below the threshold per unit time. For example, when calculating the communication load using the wireless connection success rate and the voice connection success rate, the frequency at which the wireless connection success rate falls below the threshold per unit time and the voice connection success rate at the threshold per unit time. The communication load is calculated based on the lower frequency. Here, the threshold value set for the wireless connection success rate and the threshold value set for the voice connection success rate may be the same value or different values. Further, the small base station 10 may calculate the communication load by weighted evaluation of the frequency at which each of the two or more KPIs falls below the threshold per unit time. For example, when the small base station 10 is installed in a hotel lobby or a store where there are many people coming and going and the load fluctuates, the wireless connection success rate and the location success rate are higher than the voice connection success rate and the packet connection success rate. The communication load may be weighted by placing a weight on the side. On the other hand, when the small base station 10 is installed in a home or office where high communication quality is required with few people coming and going, the voice connection success rate and the packet connection are higher than the wireless connection success rate and the location success rate. The communication load may be weighted and evaluated by placing a weight on the success rate.

  In step 402, the small base station 10 determines whether or not the communication load exceeds a threshold value. For example, when the frequency at which any one of the above four KPI values falls below the threshold per unit time exceeds the threshold, or the frequency at which any two or more KPI values fall below the threshold per unit time If it exceeds, it is determined that the communication load exceeds the threshold. In step 403, the small base station 10 reduces the cell size by lowering the radio transmission output. In step 404, the small base station 10 increases the cell size by increasing the radio transmission output.

  The computer program for executing each of steps 401 to 404 is stored in a computer-readable recording medium mounted in the control unit 14 and is interpreted and executed by a processor in the control unit 14. The This computer program describes, for example, a module consisting of a subroutine describing a process for calculating a communication load (step 401), and a process for determining whether or not the communication load exceeds a threshold (step 402). This is a software module comprising a module comprising a subroutine, a module comprising a subroutine describing a process for reducing wireless transmission output (step 403), and a module comprising a subroutine describing a process for raising wireless transmission output (step 404). . However, the functions of steps 401 to 404 are not necessarily realized by software modules, and a part or all of them may be realized by hardware modules of the small base station 10.

  “Computer-readable recording medium” refers to a storage resource such as a flexible disk, a magneto-optical disk, a ROM, a writable nonvolatile memory such as a flash memory, a portable medium such as a DVD, and a hard disk built in a computer system. That means. A “computer-readable recording medium” temporarily stores a program such as a volatile memory inside a computer system as a server or client when the program is transmitted via a network such as the Internet or a communication line such as a telephone line. It also includes those that are held on the market. The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information such as a network such as the Internet or a communication line such as a telephone line.

  In addition, when the state where the communication load of the small base station 10 becomes higher than the allowable range is constantly maintained, it is considered that there is a high necessity for the addition of the small base station 10, and the small size is given to the mobile communication provider. It is desirable to encourage the review of the base station 10 installation plan. From this point of view, the small base station 10 notifies the management server 70 of an alarm when the frequency at which the KPI value falls below the threshold per unit time exceeds the threshold, and prompts the operator to add a small base station 10. You may comprise. In addition, two thresholds with different values are set in the KPI used to calculate the communication load, and the frequency at which the KPI value falls below the threshold per unit time (the larger of the above two thresholds) exceeds the threshold. At the time, the small base station 10 notifies the management server 70 of an alarm, and when the frequency at which the KPI value falls below a threshold value (the smaller one of the above two threshold values) per unit time exceeds the threshold value, the small base station 10 10 may lower the radio transmission output. In this way, by using two thresholds having different values, it is possible to warn the operator in advance with a sufficient margin while suppressing an excessive output limit of the small base station 10, thereby improving customer satisfaction. Can do.

DESCRIPTION OF SYMBOLS 10 ... Small base station 11 ... Antenna 12 ... RF processing part 13 ... Protocol conversion part 14 ... Control part 15 ... Communication interface 21, 22 ... Mobile device 30, 30A, 30B ... Cell 31 ... Indoor 41 ... Wired line 40 ... IP network 50 ... Gateway 60 ... Core network 70 ... Management server

Claims (4)

Frequency at which any one of wireless connection success rate, in-zone success rate, voice connection success rate, and packet connection success rate falls below the threshold per unit time, or any two or more of them fall below the threshold per unit time A calculation means for calculating the communication load based on the frequency ;
Adjusting means for dynamically adjusting the wireless transmission output so as to reduce the communication load;
A small base station. The small base station according to claim 1,
The calculation means weights and evaluates the frequency at which any two or more of the wireless connection success rate, the location success rate, the voice connection success rate, and the packet connection success rate fall below a threshold per unit time. And calculating the communication load. Frequency at which any one of wireless connection success rate, in-zone success rate, voice connection success rate, and packet connection success rate falls below the threshold per unit time, or any two or more of them fall below the threshold per unit time Calculate communication load based on frequency ,
A wireless transmission output adjustment method for dynamically adjusting a wireless transmission output of the small base station so that the communication load is reduced. A computer program for causing a small base station to execute the wireless transmission output adjustment method according to claim 3 .

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