JP2020178174A - Base station equipment, communication methods and programs - Google Patents

Abstract

Kind Code: A1 A communication parameter is more easily set for each cell in order to realize higher quality in communication between a base station apparatus and a user apparatus in a radio communication system. A base station apparatus is capable of communicating with user equipment in a wireless communication system. At least one of the number of repeated transmissions at the coverage extension level and the received power threshold for determining the coverage extension level is set so that the parameter indicating the communication quality between the base station apparatus and the user apparatus is equal to or greater than a predetermined value. Equipped with a changing control unit. [Selection drawing] Fig. 8

Description

The present invention relates to base station devices, communication methods and programs for wireless communication.

In 3GPP (Third Generation Partnership Project), which is a standardization project for mobile communication systems, a power-saving wide area wireless network (LPWA: Low Power Wide Area) has already been standardized.

Non-Patent Document 1 describes NB-IoT (Narrow Band Internet of Things) and eMTC (enhanced Machine Type Communication) as LTE standards (hereinafter collectively referred to as LPWA standards) that realize cellular LPWA for IoT devices. Details regarding standardization are disclosed.

In the LPWA standard, when the user device is an MTC (Machine Type Communication) terminal, the transmission / reception bandwidth of the data channel is limited to 6PRB (Physical Resource Block). Further, when the user device is an IoT (Internet of Things) terminal, the transmission / reception bandwidth is limited to 1 PRB. By complying with the LPWA standard, it is expected that low power consumption can be achieved at low cost.

Further, as one of the functions of LPWA, there is a function called Extended Coverage. Extended coverage is a function standardized by 3GPP, and realizes improvement of communication quality by repeated transmission of signals and expansion of coverage.

Non-Patent Document 2 discloses a technique for improving communication quality and extending coverage by repeatedly transmitting signals in NB-IoT and eMTC.

In the extended coverage function of eMTC, four coverage extension levels (Coverage Enhancement Level) are defined according to how much the coverage is extended. In addition, three coverage extension levels are defined in NB-IoT.

The base station apparatus broadcasts including an RSRP (Reference Signal Received Power) threshold (rsrp-Thresholds) for determining the coverage extension level and a number of signal transmission repetitions (Repetition Number) set for each coverage extension level. The information is notified to the user device by SIB2 (System Information Block Type 2).

The user device determines the coverage extension level to be applied based on the measurement result of the received power (RSRP) of the signal received from the base station device and the received broadcast information, and repeats corresponding to the coverage extension level. Start communication by the number of times.

In general, the radio wave environment is affected by obstacles existing in the vicinity and other radio waves that interfere with the radio waves. Therefore, the communication quality of wireless communication, which is affected by the environment, differs depending on the cell. Therefore, in order to further improve the communication quality, it is desirable to set the above-mentioned RSRP threshold value and the number of times of repeating signal transmission for each cell in which the user device can be located.

The Mobile Broadband Standard, http://www.3gpp.org/news-events/3gpp-news/1805-iot_r14 Technology overview and sharing study of eMTC and NB-IoT, http://www.soumu.go.jp/main_content/000458171.pdf

However, since the number of cells set corresponding to the base station device is enormous, the radio wave environment of each cell is determined, and communication such as the above RSRP threshold value suitable for each cell and the number of times of signal transmission is repeated. It is difficult to set the parameters manually.

The present invention has been made in view of the above, and an object of the present invention is to provide a technique for more easily setting communication parameters for each cell in order to realize higher communication quality.

The base station apparatus according to one aspect of the present invention can communicate with the user apparatus in the wireless communication system, and the number of repeated transmissions at the coverage expansion level and the coverage expansion level so that the parameter indicating the communication quality becomes a predetermined value or more. A control unit for changing at least one of the received power thresholds for determining the above is provided.

According to this aspect, it is possible to more easily set the communication parameter for each cell in order to realize higher communication quality.

The communication method according to one aspect of the present invention is a communication method implemented by a base station device capable of communicating with a user device in a wireless communication system. The communication method includes changing at least one of the number of repeated transmissions at the coverage extension level and the threshold of received power for determining the coverage extension level so that the parameter indicating the communication quality becomes a predetermined value or more. ..

The program according to one aspect of the present invention is a base station device capable of communicating with a user device in a wireless communication system, and repeatedly transmits a computer at a coverage extension level so that a parameter indicating communication quality becomes a predetermined value or more. This is a program for functioning as a control unit for changing at least one of the number of times and the threshold of received power for determining the coverage extension level.

According to the present invention, it is possible to provide a technique for setting communication parameters for each cell more easily in order to realize higher communication quality.

It is a schematic diagram which shows the structure of the wireless communication system which concerns on one Embodiment. It is a conceptual diagram for demonstrating coverage extension which concerns on one Embodiment. It is a conceptual diagram for demonstrating coverage extension which concerns on one Embodiment. It is a conceptual diagram for demonstrating the repeated transmission of a signal which concerns on one Embodiment. It is a block diagram which shows the functional structure of the base station apparatus which concerns on one Embodiment. It is a figure which shows an example of the data which is stored in the storage part of the base station apparatus in one Embodiment. It is a figure which shows an example of the data which is stored in the storage part of the base station apparatus in one Embodiment. It is a figure which shows the flow of the processing by the base station apparatus which concerns on one Embodiment. It is a block diagram which shows the hardware composition of the base station apparatus which concerns on one Embodiment.

Embodiments of the present invention will be described with reference to the accompanying drawings. In each figure, those having the same reference numerals have the same or similar configurations.

〔System configuration〕
A configuration example of the wireless communication system according to the present embodiment will be described with reference to FIG. The wireless communication system 1 includes a base station device 10, a user device 21, and a user device 22. The wireless communication system 1 includes, but is not limited to, one base station device and two user devices in this example. The wireless communication system 1 may include a plurality of base station devices. Further, the wireless communication system 1 may be provided with one user device or may be provided with three or more user devices. In the following description, when the user device 21 and the user device 22 are not distinguished, the user device 21 or the user device 22 may be collectively referred to as the user device 20.

The wireless communication system 1 is capable of communication based on eMTC and NB-IoT. The wireless communication system 1 is particularly assumed to be a system compliant with LTE (Long Term Evolution), but is not limited to these, and a system compliant with other communication methods can be applied.

The base station device 10 can establish wireless communication with the user device 20. The base station device 10 has a function of performing communication in accordance with the coverage extension level.

The user device 20 is an MTC terminal or an IoT terminal. The user device 20 is a device having a function of performing communication in accordance with the coverage extension level, and is, for example, a wearable terminal, an electric meter, a GPS device, or the like.

[Overview of coverage extension]
An outline of the coverage extension function will be described with reference to FIGS. 2 to 4.

FIG. 2 shows the coverage extension level (CE Level) of eMTC. As shown in the figure, the eMTC defines four levels of coverage extension from 0 to 3. As the level goes up from level 0, the coverage (communication range) is expanded more widely. Further, CE Levels 0 and 1 are referred to as mode-A. CE Levels 2 and 3 are referred to as mode-B.

FIG. 3 shows the coverage expansion level of NB-IoT. As shown in the figure, NB-IoT defines three levels of coverage extension from 0 to 2. As the level goes up from level 0, the coverage is expanded more widely.

FIG. 4 conceptually shows Repetition in eMTC and NB-IoT. In eMTC and NB-IoT, coverage can be extended by repeatedly transmitting the same signal.

In the figure, it is shown that the same signal is repeatedly transmitted eight times in eMTC or NB-IoT. The higher the number of iterations, the greater the coverage and the better the communication quality. On the other hand, as the number of repetitions increases, the communication throughput decreases. Therefore, the number of iterations needs to be set in consideration of the trade-off between communication quality and throughput.

[Functional configuration]
The functional configuration of the base station apparatus 10 will be described with reference to FIG. As shown in the figure, the base station apparatus 10 includes a storage unit 110, a transmission unit 111, a reception unit 112, and a control unit 113. It should be noted that the figure merely shows the functional units particularly related to the embodiment of the present embodiment, and the base station apparatus 10 has, for example, other functional portions included in a general base station apparatus.

The storage unit 110 stores various data such as data set for the processing to be executed, data of the execution result, and data received by the base station apparatus 10. The storage unit 110 stores, for example, the data referred to for selecting the coverage extension level and the number of repeated transmissions (Repetition Number) applied in the communication between the base station device 10 and the user device 20.

FIG. 6 shows an example of the data used for selecting the coverage extension level as an example of the data stored in the storage unit 110. The figure shows the data set in SIB2 of the broadcast information (notification information) transmitted from the base station apparatus 10 to the user apparatus 20 in each of the eMTC and the NB-IoT.

Specifically, for eMTC, the RSRP threshold value associated with the selected coverage extension level (Selected CE Level) is stored for the item RSRP-ThresholdsPrachInfoList of the data included in SIB2. Further, for NB-IoT, the RSRP threshold value associated with the coverage extension level is stored for the item RSRP-Thresholds NPRACH-InfoList-NB of SIB2.

An example of how to use the data shown in FIG. 6 will be described. In the case of eMTC, an RSRP threshold value (hereinafter referred to as “RSRP threshold value for eMTC”) is set in RSRP-ThresholdsPrachInfoList of SIB2 in association with each coverage extension level based on the data stored in the storage unit 110. .. The RSRP threshold for eMTC is a threshold for selecting the applicable coverage extension level. FIG. 6 shows that the coverage extension level is CE Level 0 when it is equal to or higher than the set RSRP threshold value for eMTC, and the coverage extension level is CE Level 1 when it is less than the RSRP threshold value for eMTC. ..

Specifically, the user apparatus 20 measures the RSRP of the signal received from the base station apparatus 10, and further refers to the RSRP threshold value for eMTC included in the SIB2 of the broadcast information received from the base station apparatus 10. The user apparatus 20 selects the coverage extension level to be applied based on the comparison result between the measured RSRP value and the RSRP threshold value for eMTC. The user apparatus 20 communicates with the base station apparatus 10 by the number of repetitions of signal transmission corresponding to the selected coverage expansion level.

Further, in the case of NB-IoT, based on the data shown in FIG. 6 stored in the storage unit 110, the RSRP threshold value of RSRP-ThresholdsNPRACH-InfoList-NB of SIB2 (hereinafter, “RSRP threshold value for NB-IoT””. ) Is set in association with each coverage extension level. When the user apparatus 20 measures the RSRP of the signal received from the base station apparatus 10, the user apparatus 20 refers to the RSRP threshold value for NB-IoT included in SIB2 and selects the coverage extension level to be applied.

FIG. 7 shows an example of the number of repetitions of signal transmission applied at each coverage extension level as an example of the data stored in the storage unit 110. In the figure, for each of eMTC and NB-IoT, the data items (1) to (8) and (1) to (4) included in SIB2 and the signal transmission associated with each coverage extension level are shown. The number of repetitions is shown. The number of repeated signal transmissions shown in the figure is set for each data item of SIB2 and transmitted to the user apparatus 20. The user apparatus 20 determines the number of repetitions of signal transmission associated with each coverage extension level based on the data set in SIB2 included in the received broadcast information.

The number of repetitions of signal transmission can be set for any of the items shown in FIG. 7, and for example, for each of eMTC and NB-IoT, predetermined repetitions of items (2), (3), and (4) can be set. Setting the number can be mentioned.

Returning to the description of FIG. The transmission unit 111 generates various signals of the physical layer from the signals of the upper layer to be transmitted from the base station apparatus 10, and wirelessly transmits them. Further, the transmission unit 111 transmits the SIB2 of the broadcast information (notification information) generated by the base station device 10 to the user device 20. Further, the transmission unit 111 transmits a signal at a number of repetitions corresponding to the applied coverage extension level.

The receiving unit 112 receives various radio signals from the user device 20 and acquires a signal of a higher layer from the received signal of the physical layer. In addition, the receiving unit 112 receives the transmitted signal at the number of repetitions corresponding to the applied coverage extension level.

The control unit 113 controls various processes in the base station apparatus 10, such as signal transmission by the transmission unit 111, signal reception by the reception unit 112, and generation of transmitted information such as broadcast information.

For example, the control unit 113 sets at least one of the number of repeated transmissions at the coverage extension level and the threshold value of the received power (RSRP) for determining the coverage extension level so that the parameter indicating the communication quality becomes a predetermined value or more. change. The change width can be set arbitrarily. Further, the control unit 113 may change the number of repeated transmissions and the RSRP threshold value immediately after the parameter indicating the communication quality becomes less than a predetermined value, or may change the predetermined period (for example, 10 minutes, 1 hour). , Or one day), the above change may be made when the parameter indicating the communication quality becomes less than the predetermined value. When SIB2 is changed, the user device is notified of the change. For example, the notification may be performed using PAGING.

The parameter indicating the communication quality includes, for example, the connection rate in a predetermined period of communication between the base station device 10 and the user device 20. The connection rate is the ratio of the number of successful connections to the number of attempts to connect. In addition, the parameter indicating the communication quality includes the connection failure rate or the number of failures in a predetermined period. Connection failures are counted, for example, when they do not receive a response to the message sent in the RACH (Random Access Channel) procedure. The connection failure rate is the ratio of the number of connection failures to the number of connection attempts.

The number of repeated transmissions at the coverage expansion level by the control unit 113 and the change of the threshold value of the received power (RSRP) for determining the coverage expansion level can be changed by, for example, the storage unit 110 as described with reference to FIGS. 6 and 7. This is done by changing the data stored in.

Specifically, the more the RSRP threshold is changed to be raised, the higher the communication quality is. Further, the communication quality is improved as the number of repeated transmissions is changed.

The control unit 113 generates broadcast information including the number of repeated transmissions at the changed coverage expansion level and the threshold value of the received power for determining the coverage expansion level, and controls the transmission of the broadcast information by the transmission unit 111. .. How to include the number of repeated transmissions and the threshold value of the received power in the broadcast information has already been described with reference to FIGS. 6 and 7.

In general, the number of cells to be set corresponding to the base station apparatus is enormous. Therefore, it is difficult to judge the radio wave environment of each cell and manually set communication parameters such as the above-mentioned RSRP threshold value and the number of times of repeating signal transmission suitable for each cell.

On the other hand, according to the present embodiment, when the parameter indicating the communication quality is less than a predetermined value, the control unit 113 of the base station apparatus 10 has a communication parameter such as the number of repeated transmissions and the threshold value of RSRP. Control to raise at least one of them. As a result, communication parameters can be set more easily for each cell in order to realize higher communication quality.

Further, the control unit 113 may control to lower at least one of the number of repeated transmissions and the threshold value of RSRP when the parameter indicating the communication quality is equal to or higher than the predetermined value for a predetermined period.

As described above, as the number of repetitions of signal transmission increases, the coverage is further expanded and the communication quality improves, while as the number of repetitions increases, the communication throughput decreases. Therefore, when the communication quality is above a certain level, lowering at least one of the number of repeated transmissions and the RSRP threshold prevents the communication quality from becoming excessively high, and between the communication quality and the throughput. Can be balanced.

[Processing flow]
An example of the processing flow executed by the base station apparatus 10 will be described with reference to FIG. This process is controlled by the processor of the base station apparatus 10 executing a computer program stored in the storage unit. Details of the processing already described will be omitted here.

First, in S11, the base station apparatus 10 determines whether or not a parameter (for example, a connection rate) indicating the quality of wireless communication between the base station apparatus 10 and the user apparatus 20 is less than a predetermined value for a predetermined period. to decide. If it is less than the predetermined value for a predetermined period, the process proceeds to S12, and if it is more than the predetermined value, the process proceeds to S13.

In S12, the base station apparatus 10 is changed to increase at least one of the parameters included in SIB2, the number of repeated transmissions at the coverage extension level and the threshold value of received power (RSRP) for determining the coverage extension level. , The communication quality is improved by notifying the user device of the change.

Next, in S13, the base station apparatus 10 determines whether or not a parameter (for example, connection rate) indicating the quality of wireless communication is equal to or greater than a predetermined value for a predetermined period. When the value is equal to or greater than the predetermined value for a predetermined period, the process proceeds to S14, and when the value is less than the predetermined value, the process proceeds to S11.

In S14, the base station apparatus 10 is changed so as to lower at least one of the number of repeated transmissions at the coverage extension level and the threshold value of the received power for determining the coverage extension level among the parameters included in SIB2, and the user apparatus. Properly secure wireless resources by notifying the change.

As described above, according to the present embodiment, when the parameter indicating the communication quality is less than a predetermined value, the base station apparatus 10 has, for example, at least one of the number of repeated transmissions and the threshold value of RSRP. Control to raise. As a result, communication parameters can be set more easily for each cell in order to realize higher communication quality.

Further, the base station apparatus 10 controls so as to lower at least one of the number of repeated transmissions and the threshold value of RSRP when the parameter indicating the communication quality is equal to or higher than the predetermined value for a predetermined period.

In general, the greater the number of repetitions of signal transmission, the better the communication quality, while the greater the number of repetitions, the lower the communication throughput. Therefore, when the communication quality is above a certain level, lowering at least one of the number of repeated transmissions and the RSRP threshold prevents the communication quality from becoming excessively high, and between the communication quality and the throughput. Can be balanced.

[Hardware configuration]
An example of the hardware configuration of the base station apparatus 10 will be described with reference to FIG. The function of the base station apparatus 10 described above is realized by, for example, the hardware configuration shown in the figure.

In the following description, the word "device" can be read as a circuit, device, unit, or the like. The hardware configuration of the base station device 10 may be configured to include one or more of the devices shown in FIG. 9, or may be configured not to include some of the devices.

As shown in FIG. 9, the base station device 10 includes a processor 11, a memory 12, a storage device 13, a communication device 14, an input device 15, and an output device 16.

The processor 11 controls the entire processing by the base station apparatus 10. The processor 11 includes, for example, a CPU (Central Processing Unit), a microprocessor, a digital signal processor (DSP: Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic), a PLC (Programmable Logic), and a PLD (Programmable Logic). It may be configured to include hardware such as Array).

The memory 12 is a computer-readable recording medium, and is, for example, a ROM (Read Only Memory), an EPROM (Erasable Program ROM), an EEPROM (Electrically Erasable Program ROM), a RAM (Random Access Memory), or a RAM (Random Access Memory). May be done. The memory 12 stores a computer program, a software module, and the like that can execute the processing by the base station apparatus 10 in the above embodiment.

The storage device 13 is a computer-readable recording medium, and may be composed of at least one such as a hard disk drive, a flexible disk, a digital versatile disk, a smart card, a flash memory, and a magnetic strip.

The communication device 14 is a device for performing communication between computers via a wireless communication network. The communication device 14 is also referred to as, for example, a network device, a network controller, a network card, or a communication module.

The input device 15 is a device (for example, a switch, a button, a sensor, etc.) that receives an input from the outside. The output device 16 is a device (for example, a display, a speaker, an LED lamp, etc.) that outputs to the outside.

Further, each device such as the processor 11 and the memory 12 is connected by a bus for communicating information. The bus may be composed of a single bus, or may be composed of different buses between devices.

The embodiments described above are for facilitating the understanding of the present invention, and are not for limiting and interpreting the present invention. Each element included in the embodiment and its arrangement, material, condition, shape, size, etc. are not limited to those exemplified, and can be changed as appropriate. In addition, the configurations shown in different embodiments can be partially replaced or combined.

1 ... Wireless communication system, 10 ... Base station equipment, 21, 22 ... User equipment

Claims (9)

A base station device capable of communicating with a user device in a wireless communication system.
A base station apparatus including a control unit that changes at least one of a threshold value of received power for determining the number of repeated transmissions at the coverage expansion level and the coverage expansion level so that a parameter indicating communication quality becomes a predetermined value or more. The base station apparatus according to claim 1, further comprising a transmission unit that transmits broadcast information including the number of repeated transmissions changed by the control unit or the threshold value of the received power to the user apparatus. The base station device according to claim 1 or 2, wherein the parameter includes a connection rate of communication between the base station device and the user device. The invention according to any one of claims 1 to 3, wherein the control unit raises at least one of the number of repeated transmissions and the threshold value of the received power when the parameter is less than a predetermined value for a predetermined period. Base station equipment. The control unit according to any one of claims 1 to 4, wherein the control unit lowers at least one of the number of repeated transmissions and the threshold value of the received power when the parameter is equal to or higher than a predetermined value for a predetermined period. Base station equipment. The base station apparatus according to any one of claims 1 to 5, wherein communication by the wireless communication system is based on eMTC (enhanced Machine Type Communication). The base station apparatus according to any one of claims 1 to 5, wherein the communication by the wireless communication system is based on NB-IoT (Narrow Band Internet of Things). There is a communication method implemented by a base station device capable of communicating with a user device in a wireless communication system.
A communication method comprising changing at least one of a number of repeated transmissions at a coverage extension level and a threshold of received power for determining the coverage extension level so that a parameter indicating communication quality becomes a predetermined value or more. Computer,
A base station device capable of communicating with a user device in a wireless communication system.
A program for functioning as a control unit that changes at least one of the number of repeated transmissions at the coverage extension level and the threshold value of the received power for determining the coverage extension level so that the parameter indicating the communication quality becomes a predetermined value or more. ..

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