JP5705595B2 - Wireless terminal and control method - Google Patents

Description

  The present invention relates to a wireless terminal and a control method that support MDT.

  In a mobile communication system, the reception signal state (for example, reception power and reception quality) in the area changes because the building is installed in the area of the base station. Using a vehicle, a drive test is performed to collect position information at the time of measurement while measuring a received signal state.

  When the operator finds a position or an area where the reception signal state deteriorates (that is, a coverage problem) by such a drive test, the operator performs network optimization for solving the found coverage problem. Here, network optimization means, for example, changing parameters of a base station or newly installing a base station.

  Since the drive test involves many man-hours and high costs, the 3GPP (3rd Generation Partnership Project), which is a standardization project for mobile communication systems, uses a wireless terminal owned by the user to measure and position the received signal. The specification of MDT (Minimization of Drive Test) for automating information collection is being developed (see Non-Patent Documents 1 and 2).

  A wireless terminal configured to perform MDT measures a received signal state, and reports measurement data including information on the result of the measurement and position information at the time of measurement to the mobile communication network. The MDT performed while the wireless terminal is performing communication is referred to as an immediate report type (Immediate MDT), and the MDT performed while the wireless terminal is waiting is referred to as a recording type (Logged MDT).

3GPP TR 36.805 V9.0.0: “Study on Minimization of drive-tests in Next Generation Networks”, 2009-12 3GPP TS 37.320 V10.0.0: “Radio measurement collection for Minimization of Drive Tests (MDT); Overall description; Stage 2”, 2010-12

  By the way, some coverage problems cannot be solved even if normal network optimization is performed, depending on factors that cause deterioration of the received signal state. For example, the problem that the reception signal state rapidly deteriorates when the wireless terminal moves into the elevator and closes its door cannot be solved even by performing normal network optimization.

  Therefore, it is preferable to exclude such coverage problems from network optimization. However, in the current MDT specifications, measurement data regarding such coverage problems are also reported from the wireless terminal to the mobile communication network. May induce inappropriate network optimization. Moreover, it is not preferable that the load of the wireless terminal and the consumption of the wireless resource increase by reporting such unnecessary measurement data to the mobile communication network.

  Therefore, an object of the present invention is to provide a wireless terminal and a control method that can avoid inappropriate network optimization and increase in load and resource consumption.

  In order to solve the above-described problems, the present invention has the following features.

  First, the wireless terminal according to the present invention is characterized by a wireless communication unit (wireless communication unit 110) capable of performing wireless communication with a mobile communication network (for example, E-UTRAN 10), and a received signal state from the mobile communication network. A control unit (control unit 120) that controls measurement data including information on a received signal state measured by the measurement unit and position information at the time of measurement to the mobile communication network 150), and when the control unit detects a sudden change (for example, deterioration) in the received signal state measured by the measuring unit, the measurement data corresponding to the received signal state indicating the sudden change. Is excluded from being reported to the mobile communication network.

  According to such a feature, when the wireless terminal detects a sudden change in the received signal state, the wireless terminal excludes measurement data corresponding to the received signal state indicating the sudden change from a report target to the mobile communication network. For this reason, for example, when the wireless terminal moves into the elevator and the door is closed, it is not necessary to report measurement data regarding the coverage problem that the reception signal state deteriorates rapidly to the mobile communication network. Can be excluded from network optimization. Therefore, the wireless terminal according to the above characteristics can avoid inducing inappropriate network optimization and increasing load and resource consumption.

  Another feature of the radio terminal according to the present invention is that, in the above feature, the sudden change in the received signal state is that the power level of the received signal from the mobile communication network has decreased by a predetermined amount within a predetermined time. This is the gist.

  Another feature of the wireless terminal according to the present invention is that, in the above feature, the control unit controls to report the measurement data to the mobile communication network when a report condition is satisfied, and the report condition is: The gist is that the time when the power level of the received signal falls below the threshold exceeds a certain time, and the predetermined time is shorter than the certain time.

  Another feature of the wireless terminal according to the present invention is that, in the above feature, the control unit causes the power level of the received signal to exceed a threshold after the power level of the received signal has decreased by the predetermined amount within the predetermined time. Up to this point, the gist is to control to continue the state in which the reporting of the measurement data to the mobile communication network is stopped.

  Another feature of the wireless terminal according to the present invention is that, in the above feature, the measurement of the reception signal state and the reporting of the measurement data are performed in a state in which the wireless terminal is performing communication.

  A feature of the control method according to the present invention is a control method for controlling a wireless terminal capable of performing wireless communication with a mobile communication network, the step of measuring a received signal state from the mobile communication network, and the measurement When the received signal state measured in the step of measuring does not indicate rapid deterioration, measurement data including information on the received signal state measured in the measuring step and position information at the time of measurement is sent to the mobile communication network And when the received signal state measured in the measuring step shows rapid deterioration, the measurement data corresponding to the received signal state indicating the rapid deterioration is reported to the mobile communication network. And a step of excluding from the above.

  ADVANTAGE OF THE INVENTION According to this invention, the radio | wireless terminal and control method which can avoid improper network optimization inducing or a load and resource consumption increasing can be provided.

1 is an overall schematic configuration diagram of a mobile communication system according to an embodiment of the present invention. It is a block diagram which shows the structure of the radio | wireless terminal which concerns on embodiment of this invention. It is a figure for demonstrating the operation | movement which detects the rapid fall of RSRP. It is a flowchart which shows operation | movement of the radio | wireless terminal which concerns on embodiment of this invention.

  Referring to the drawings, (1) Outline of mobile communication system, (2) Configuration of radio terminal, (3) Operation of radio terminal, (4) Effects of embodiment, (5) Others These will be described in the order of the embodiments. In the drawings in the following embodiments, the same or similar parts are denoted by the same or similar reference numerals.

(1) Overview of Mobile Communication System FIG. 1 is an overall schematic configuration diagram of a mobile communication system 1 according to the present embodiment. The mobile communication system 1 is configured based on LTE (Long Term Evolution) whose specifications are defined by 3GPP, and supports the above-described Immediate MDT.

  As shown in FIG. 1, the mobile communication system 1 includes a radio terminal UE, an E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) 10, a mobility management device MME / gateway device S-GW, and a maintenance monitoring device OAM. Have The E-UTRAN 10 is a mobile communication network configured by a plurality of base stations eNB.

  The radio terminal UE is a portable radio communication device possessed by a user. The radio terminal UE is connected to any of the base stations eNB configuring the E-UTRAN 10 (including when the radio terminal UE is connected via a relay device or when connected to the relay device), and the base station eNB It is comprised so that communication with a communication destination can be performed via. A state in which the radio terminal UE is executing communication is referred to as a connected mode.

  Each base station eNB is a fixed radio communication device installed by an operator, and is configured to perform radio communication with the radio terminal UE. Each base station eNB performs communication with the mobility management device MME / gateway device S-GW and communication with the maintenance monitoring device OAM via the backhaul.

  The mobility management device MME is configured to perform various types of mobility control for the radio terminal UE, and the gateway device S-GW is configured to perform transfer control of user data transmitted and received by the radio terminal UE.

  The maintenance monitoring device OAM is a server device installed by an operator, and is configured to perform maintenance and monitoring of the E-UTRAN 10.

  In the present embodiment, the base station eNB to which the radio terminal UE is connected transmits information for setting the Immediate MDT to the radio terminal UE, for example, in response to an instruction from the maintenance monitoring apparatus OAM.

  The radio terminal UE set to perform Immediate MDT measures the state of a received signal from the E-UTRAN 10 in the connected mode, and reports the measurement data to the E-UTRAN 10. Hereinafter, the process in which the radio terminal UE appropriately generates measurement data is referred to as “measurement collection”.

  In this embodiment, reference signal received power (RSRP) is used as one index of the received signal state, but reference signal received quality (RSRQ) may be used together with RSRP.

  The measurement data includes information related to measurement results and position information at the time of measurement. The information related to the measurement result is information indicating RSRP for each cell of one or a plurality of base stations eNB, for example. The location information is GPS / GNSS location information when the radio terminal UE has a GPS / GNSS function, and is RF fingerprint information when the radio terminal UE does not have a GPS reception function. .

  The base station eNB that has received the measurement data from the radio terminal UE transfers the received measurement data to the maintenance monitoring device OAM. When the maintenance monitoring device OAM finds a coverage problem based on the measurement data obtained in this manner, the maintenance monitoring device OAM automatically performs network optimization for notifying the operator of the found coverage problem or eliminating it.

  When setting the Immediate MDT in the radio terminal UE, the base station eNB that performs the setting can specify various parameters related to the Immediate MDT. In the present embodiment, it is assumed that the base station eNB that performs the setting specifies a reporting condition (Reporting trigger) that is one of Immediate MDT parameters. The reporting condition means a trigger for the radio terminal UE to report measurement data to the E-UTRAN 10.

  Some coverage problems cannot be resolved even if normal network optimization is performed, depending on factors that degrade RSRP. For example, the problem that RSRP rapidly deteriorates when the radio terminal UE moves into an elevator and its door is closed cannot be solved even by performing normal network optimization. Therefore, it is preferable that such a coverage problem is not subject to network optimization.

  Therefore, in the present embodiment, when the radio terminal UE configured to perform Immediate MDT detects a rapid decrease in RSRP in the connected mode, the measurement data corresponding to the RSRP indicating the rapid decrease is transmitted to the E-UTRAN10. Excluded from reporting to.

(2) Configuration of Radio Terminal FIG. 2 is a block diagram showing a configuration of the radio terminal UE according to the present embodiment. Here, an example in which the radio terminal UE has a GPS function will be described.

  As shown in FIG. 2, the radio terminal UE includes an antenna 101, a radio communication unit 110, a measurement unit 120, a GPS receiver 130, a storage unit 140, a control unit 150, an internal timer 160, and a battery 170. And have.

  The antenna 101 is used for transmission / reception of a radio signal. The wireless communication unit 110 is configured using, for example, a radio frequency (RF) circuit, a baseband (BB) circuit, or the like, and configured to perform wireless communication via the antenna 101. For transmission, the wireless communication unit 110 encodes and modulates a transmission signal input from the control unit 150, performs up-conversion and amplification, and outputs the result to the antenna 101. For reception, the radio communication unit 110 performs amplification and down-conversion of the reception signal input from the antenna 101, performs demodulation and decoding, and outputs the result to the control unit 150.

  The measurement unit 120 measures the reception power level of the radio signal (specifically, the reference signal) received by the radio communication unit 110 from the E-UTRAN 10, that is, RSRP, and measures the measured RSRP (hereinafter referred to as “RSRP measurement value”). Output to the control unit 150. The RSRP measurement value may be the RSRP of only the serving cell, or may be the average or total of RSRP for each cell.

  The GPS receiver 130 receives a signal from a GPS satellite and outputs position information based on GPS to the control unit 150.

  The storage unit 140 is configured using a memory, for example, and stores various types of information used for controlling the radio terminal UE and the like. The memory | storage part 140 memorize | stores the various threshold values for detecting the rapid fall of RSRP, etc., and the setting information regarding Immediate MDT. In the present embodiment, the various threshold values include an RSRP threshold value A, an RSRP threshold value B, an internal timer threshold value A, and an internal timer threshold value B. Details of each threshold will be described later.

  The control unit 150 is configured using, for example, a CPU, and controls various functions provided in the radio terminal UE.

  The control unit 150 generates measurement data in which the RSRP measurement value input from the measurement unit 120 and the position information input from the GPS receiver 130 are associated with each other according to the setting information stored in the storage unit 140.

  In addition, the control unit 150 controls the wireless communication unit 110 to report measurement data generated by measurement collection to the E-UTRAN 10 according to a reporting condition that is one of setting information stored in the storage unit 140.

  In this embodiment, Radio Link Failure (RLF) is used as a reporting condition. The RLF as a reporting condition reports when a condition that the time when the RSRP measurement value falls below the RSRP threshold A exceeds a certain time corresponding to the internal timer threshold A is satisfied. The predetermined time is defined by an internal timer threshold A.

  The internal timer 160 is used for the control unit 150 to detect a rapid decrease in RSRP. The internal timer 160 is activated when the RSRP measurement value falls below the RSRP threshold A by the control unit 150. After being started, the internal timer 160 outputs a timer value that increases as time elapses to the control unit 150.

  The battery 170 stores electric power to be supplied to each block of the radio terminal UE.

  In the radio terminal UE configured as described above, the control unit 150 uses the timer value input from the internal timer 160 and various threshold values stored in the storage unit 140 during execution of Immediate MDT, and the measurement unit A rapid drop in RSRP measurement from 120 is detected.

  In the present embodiment, the rapid decrease in the RSRP measurement value means that the RSRP measurement value has decreased by a predetermined amount corresponding to the difference between the RSRP threshold A and the RSRP threshold B within a predetermined time corresponding to the internal timer threshold B. Means. The predetermined time corresponding to the internal timer threshold B is set to a time shorter than a certain time corresponding to the internal timer threshold A.

  When detecting a rapid decrease in the RSRP measurement value, the control unit 150 performs control so as to exclude measurement data corresponding to the RSRP measurement value indicating the rapid decrease from being reported to the E-UTRAN 10. The measurement data corresponding to the RSRP measurement value indicating a rapid decrease may be measurement data at the time when a sudden decrease in the RSRP measurement value is detected, and is defined from the time when the RSRP measurement value is detected. It may be measurement data up to the time before.

  FIG. 3 is a diagram for explaining an operation of detecting a rapid decrease in the RSRP measurement value. In the figure, in order to explain the detection concept, the RSRP monotonously decreases with time.

  As shown in FIG. 3, the control unit 150 uses the Δt that is the time difference from the time when the RSRP measurement value falls below the RSRP threshold A to the time when the RSRP measurement value falls below the RSRP threshold B, Detect a drop.

  The controller 150 starts the internal timer 160 when the RSRP measurement value falls below the RSRP threshold A, and measures Δt by checking the timer value of the internal timer 160 when the RSRP measurement value falls below the RSRP threshold B. To do. When Δt is equal to or less than the RSRP threshold B, it can be determined that the RSRP has rapidly decreased.

(3) Operation of Radio Terminal FIG. 4 is a flowchart showing the operation of the radio terminal UE according to the present embodiment. This flow is started when the radio terminal UE is set from the E-UTRAN 10 to perform Immediate MDT. First, when this flow is started, the control unit 150 controls the measurement unit 120 to constantly measure RSRP.

  As shown in FIG. 4, in step S <b> 101, the control unit 150 resets the internal timer 160.

  In step S <b> 102, the control unit 150 confirms the RSRP measurement value input from the measurement unit 120.

  In step S103, the control unit 150 compares the RSRP measurement value confirmed in step S102 with the RSRP threshold A. When the RSRP measurement value confirmed in step S102 exceeds the RSRP threshold A, the control unit 150 returns the process to step S102. On the other hand, when the RSRP measurement value confirmed in step S102 is equal to or less than the RSRP threshold A, the control unit 150 advances the process to step S104. Measurement collection is performed after step S104.

  In step S104, the control unit 150 starts the internal timer 160.

  In step S <b> 105, the control unit 150 confirms the RSRP measurement value input from the measurement unit 120.

  In step S <b> 106, the control unit 150 confirms the timer value input from the internal timer 160.

  In step S107, the control unit 150 compares the RSRP measurement value confirmed in step S105 with the RSRP threshold A. When the RSRP measurement value confirmed in step S105 exceeds the RSRP threshold A, the control unit 150 returns the process to step S101. On the other hand, when the RSRP measurement value confirmed in step S105 is equal to or less than the RSRP threshold A, the control unit 150 advances the process to step S108.

  In step S108, the control unit 150 compares the timer value confirmed in step S106 with the internal timer threshold value A. If the timer value confirmed in step S106 exceeds the internal timer threshold A, the control unit 150 advances the process to step S112. On the other hand, when the timer value confirmed in step S106 is equal to or smaller than the internal timer threshold A, the control unit 150 advances the process to step S109.

  In step S112, since the RSRP measurement value does not rapidly decrease and the internal timer 160 times out and the reporting condition is satisfied, the control unit 150 controls to report the measurement data to the E-UTRAN 10. To do. Specifically, the control unit 150 outputs the measurement data to the radio communication unit 110, and the radio communication unit 110 transmits the measurement data input from the control unit 150 to the connection destination base station eNB.

  On the other hand, in step S109, the control unit 150 compares the RSRP measurement value confirmed in step S105 with the RSRP threshold value B. When the RSRP measurement value confirmed in step S105 exceeds the RSRP threshold B, the control unit 150 returns the process to step S105. On the other hand, when the RSRP measurement value confirmed in step S105 is equal to or less than the RSRP threshold B, the control unit 150 advances the process to step S110.

  In step S110, the control unit 150 compares the timer value confirmed in step S106 with the internal timer threshold value B. If the timer value confirmed in step S106 exceeds the internal timer threshold B, the control unit 150 returns the process to step S105. On the other hand, if the timer value confirmed in step S106 is equal to or smaller than the internal timer threshold value B, the RSRP measurement value has rapidly decreased, and the control unit 150 advances the process to step S111.

  In step S111, the control unit 150 stops reporting measurement data by RLF, and returns the process to step S101.

(4) Effects of the Embodiment As described above, according to the present embodiment, when the radio terminal UE configured to perform the Immediate MDT detects a sudden decrease in the RSRP measurement value in the connected mode, The measurement data corresponding to the RSRP measurement value indicating a significant decrease is excluded from the report target to the E-UTRAN 10.

  For this reason, for example, when the radio terminal UE moves into the elevator and its door is closed, it is not necessary to report measurement data related to the coverage problem that the RSRP rapidly decreases to the E-UTRAN 10. It can be excluded from optimization.

  Therefore, the radio terminal UE according to the present embodiment can avoid inducing inappropriate network optimization and increasing load and resource consumption.

  In the present embodiment, the predetermined time corresponding to the internal timer threshold B is set to a time shorter than a certain time corresponding to the internal timer threshold A. Thereby, since the rapid fall of RSRP measured value can be detected before detecting RLF, the report by RLF can be stopped appropriately.

(5) Other Embodiments As described above, the present invention has been described according to the embodiment. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the above-described embodiment, Δt, which is the time difference from the time when the RSRP measurement value falls below the RSRP threshold A to the time when it falls below the RSRP threshold B, is acquired using the internal timer 160, and Δt is equal to or less than the internal timer threshold B. It was determined whether or not the RSRP measurement value suddenly decreased depending on whether or not. However, the determination criterion is not limited to such a criterion, and a gradient of change calculated from the RSRP change amount in a certain time may be used as the criterion. For example, the amount of decrease in the RSRP measurement value within a certain period of time is acquired, the amount of decrease is compared with a threshold value, and when the amount of decrease exceeds the threshold value, it is determined that the RSRP measurement value has rapidly decreased. Also good.

  In the above-described embodiment, the operation for enabling the report to be resumed after stopping the measurement data report has not been specifically described. However, after the measurement data report is stopped, the report can be resumed. Good. In this case, the control unit 150 of the radio terminal UE performs control so as to continue the state in which the measurement data reporting is stopped until the RSRP measurement value exceeds the RSRP threshold A after detecting that the RSRP measurement value has rapidly decreased. May be.

  In the above-described embodiment, RLF is used as a reporting condition. However, the reporting condition is not limited to RLF, and other reporting conditions such as Periodic and Serving cell becomes worse than threshold (SCBWTT) may be used. Periodic is a reporting condition that reports periodically, and SCBWTT is a reporting condition that reports when RSRP measured for a serving cell falls below a threshold.

  In the above-described embodiment, the mobile communication system configured based on LTE whose specifications are defined by 3GPP has been described as an example. However, the mobile communication system is not limited to LTE, but other W-CDMA (Wideband Code Division Multiple Access) and the like. The present invention may be applied to a mobile communication system.

  In the above-described embodiment, the Immediate MDT has been mainly described. However, the present invention may be applied to a Logged MDT.

  Thus, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the invention specifying matters in the scope of claims reasonable from this disclosure.

  UE ... wireless terminal, eNB ... base station, MME ... mobility management device, OAM ... maintenance monitoring device, S-GW ... gateway device, 1 ... mobile communication system, 10 ... E-UTRAN, 101 ... antenna, 110 ... wireless communication unit 120 ... Measurement unit 130 ... GPS receiver 140 ... Storage unit 150 ... Control unit 160 ... Internal timer 170 ... Battery

Claims (3)

A wireless communication unit capable of performing wireless communication with a mobile communication network;
A measuring unit for measuring a state of a received signal from the mobile communication network;
A control unit that controls to report measurement data including information on the received signal state and position information at the time of measurement to the mobile communication network when a time during which the received signal state falls below a threshold exceeds a certain time; With
When the control unit detects a sudden drop in which the received signal state is lowered by a predetermined amount within a predetermined time shorter than the predetermined time, the control unit obtains measurement data corresponding to the received signal state indicating the sudden drop. Controlling to exclude from reporting to the mobile communication network ,
The control unit continues the state in which the measurement data reporting to the mobile communication network is stopped until the reception signal state exceeds a threshold after the reception signal state has decreased by the predetermined amount within the predetermined time. A wireless terminal characterized by performing control as follows.   The wireless terminal according to claim 1, wherein the measurement of the reception signal state and the reporting of the measurement data are performed in a state in which the wireless terminal is performing communication. A control method for controlling a wireless terminal capable of performing wireless communication with a mobile communication network,
Measuring a received signal state from the mobile communication network;
In the case where the time when the received signal state falls below the threshold exceeds a certain time,
In the case of not detecting a sudden decrease in which the received signal state decreases by a predetermined amount within a predetermined time shorter than the predetermined time, measurement data including information on the received signal state and position information at the time of measurement is obtained. Reporting to the mobile communication network;
If the sudden drop is detected, the measurement data corresponding to the received signal state indicating the sudden drop is excluded from the report target to the mobile communication network, and
The wireless terminal continues to stop reporting the measurement data to the mobile communication network until the received signal state exceeds a threshold after the received signal state has decreased by the predetermined amount within the predetermined time. The control method characterized by the above-mentioned.

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