JP2012191260A - Wireless terminal and control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid inducing inappropriate network optimization and increasing load and resource consumption.SOLUTION: According to one embodiment, a wireless terminal UE comprises: a storage unit 140; a wireless communication unit 110 capable of wireless communication with an E-UTRAN; a measuring unit 120 for measuring RSRP transmitted from the E-UTRAN; and a control unit 150 for controlling measurement data to be recorded in the storage unit 140, which includes information relating to the RSRP measured by means of the measuring unit 120 and positional information at the time of the measurement, and controlling the measurement data recorded in the storage unit 140 to be reported to the E-UTRAN. When the control unit 150 detects a rapid reduction of the RSRP measured by means of the measuring unit 120, the control unit controls all of the measurement data recorded in the storage unit 140 to be deleted.

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 storage unit (storage unit 140) and a wireless communication unit (wireless communication unit 110) capable of performing wireless communication with a mobile communication network (for example, E-UTRAN 10), Measurement data including a measurement unit (measurement unit 120) for measuring a reception signal state from the mobile communication network, information on a reception signal state measured by the measurement unit, and position information at the time of measurement is recorded in the storage unit. And a control unit (control unit 150) for controlling to report the measurement data recorded in the storage unit to the mobile communication network, the control unit receiving signal state measured by the measurement unit The gist is to perform control so as to delete all measurement data recorded in the storage unit when a sudden change (for example, deterioration) is detected.

  According to such a feature, when the wireless terminal detects a sudden change in the received signal state, the wireless terminal deletes all measurement data recorded in the storage unit. As a result, for example, when a wireless terminal moves into an elevator and its door closes, it is not necessary to report measurement data related to a 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. In addition, the storage capacity of the storage unit can be saved.

  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 record the measurement data in the storage unit according to a recording condition, and the recording condition is a power level of the received signal. Is that recording is performed for a predetermined time after the value falls below the threshold, and the predetermined time is shorter than the predetermined time.

  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 recording of the measurement data are performed while the wireless terminal is in a standby state.

  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 A step of recording measurement data including information on a received signal state measured in the step of measuring and position information at the time of measurement in a storage unit, and a case where the received signal state measured in the step of measuring shows rapid deterioration And a step of deleting all the measurement data recorded in the storage unit.

  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 Logged 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 connects to any of the base stations eNB configuring the E-UTRAN 10 (including a case of connection via a relay device or a case of connection to a relay device), and a communication destination via the base station eNB It is configured to be able to communicate with. A state in which the radio terminal UE is executing communication is referred to as a connected mode, and a state in which the radio terminal UE is waiting is referred to as an idle 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 Logged MDT in the radio terminal UE to the radio terminal UE, for example, in response to an instruction from the maintenance monitoring apparatus OAM.

  The radio terminal UE configured to perform the Logged MDT measures and records the state of the received signal from the E-UTRAN 10 in the idle mode, and reports measurement data to the E-UTRAN 10 when shifting from the idle mode to the connected mode. . 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 apparatus OAM finds a coverage problem based on the measurement data obtained in this way, the maintenance monitoring apparatus OAM performs network optimization for notifying the operator of the found coverage problem or for eliminating the coverage problem.

  When setting the Logged MDT in the radio terminal UE, the base station eNB that performs the setting can specify various parameters related to the Logged MDT. In this embodiment, it is assumed that the base station eNB that performs the setting specifies a recording condition (Logging trigger) that is one of the parameters of the Logged MDT. The recording condition means a trigger for the radio terminal UE to record measurement data.

  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 set to perform the Logged MDT detects an abrupt decrease in RSRP in the idle mode, it deletes all recorded measurement data.

(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 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 storage unit 140 stores various threshold values for detecting a rapid decrease in RSRP and the like, and setting information regarding the Logged 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. The measured data is controlled to be recorded in the storage unit 140. Then, the control unit 150 performs control so that the measurement data recorded in the storage unit 140 is reported from the wireless communication unit 110 to the E-UTRAN 10 when shifting from the idle mode to the connected mode.

  In this embodiment, Serving cell becomes worse than threshold (SCBWTT) is used as the recording condition included in the setting information. SCBWTT as a recording condition is to perform recording for a certain time after the RSRP measurement value for the serving cell falls below the RSRP threshold A. 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 the various threshold values stored in the storage unit 140 during the execution of the Logged MDT. 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. Here, the predetermined time corresponding to the internal timer threshold B is set to a time shorter than the predetermined time corresponding to the internal timer threshold A.

  Furthermore, when the controller 150 detects a rapid decrease in the RSRP measurement value, the controller 150 controls to delete all measurement data recorded in the storage unit 140.

  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 control unit 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 Logged MDT and then shifts to the idle mode. 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 S301, the control unit 150 resets the internal timer 160.

  In step S302, the control unit 150 resets the invalid data presence flag. The invalid data presence flag is a flag for specifying invalid measurement data.

  In step S <b> 303, the control unit 150 confirms the RSRP measurement value input from the measurement unit 120.

  In step S304, the control unit 150 compares the RSRP measurement value confirmed in step S303 with the RSRP threshold A. When the RSRP measurement value confirmed in step S303 exceeds the RSRP threshold A, the control unit 150 returns the process to step S303. On the other hand, when the RSRP measurement value confirmed in step S303 is equal to or less than the RSRP threshold A, the control unit 150 advances the process to step S305.

  In step S305, the control unit 150 starts the internal timer 160. In step S306, the control unit 150 starts measurement collection. Further, in step S307, the control unit 150 starts recording measurement data.

  In step S <b> 308, the control unit 150 confirms the RSRP measurement value input from the measurement unit 120.

  In step S309, the control unit 150 checks the timer value input from the internal timer 160.

  In step S310, the control unit 150 compares the RSRP measurement value confirmed in step S308 with the RSRP threshold A. When the RSRP measurement value confirmed in step S308 exceeds the RSRP threshold A, the control unit 150 advances the process to step S315. On the other hand, when the RSRP measurement value confirmed in step S308 is equal to or less than the RSRP threshold A, the control unit 150 advances the process to step S311.

  In step S311, the control unit 150 compares the timer value confirmed in step S309 with the internal timer threshold value A. If the timer value confirmed in step S309 exceeds the internal timer threshold A, the control unit 150 advances the process to step S315. On the other hand, when the timer value confirmed in step S309 is equal to or smaller than the internal timer threshold A, the control unit 150 advances the process to step S312.

  On the other hand, in step S312, the control unit 150 compares the RSRP measurement value confirmed in step S308 with the RSRP threshold value B. When the RSRP measurement value confirmed in step S308 exceeds the RSRP threshold B, the control unit 150 returns the process to step S308. On the other hand, when the RSRP measurement value confirmed in step S308 is equal to or less than the RSRP threshold B, the control unit 150 advances the process to step S313.

  In step S313, the control unit 150 compares the timer value confirmed in step S309 with the internal timer threshold value B. If the timer value confirmed in step S309 exceeds the internal timer threshold value B, the control unit 150 returns the process to step S308. On the other hand, if the timer value confirmed in step S309 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 S314.

  In step S314, the control unit 150 stores an invalid data presence flag.

  In step S315, the control unit 150 ends the measurement collection. In Step S316, control part 150 ends recording of measurement data.

  In step S317, the control unit 150 checks the presence or absence of invalid measurement data according to the presence or absence of an invalid data presence flag. If there is an invalid data presence flag, that is, if there is invalid measurement data, the control unit 150 advances the process to step S318. On the other hand, when there is no invalid data presence flag, that is, when there is no invalid measurement data, the control unit 150 returns the process to step S301.

  In step S318, the control unit 150 deletes all measurement data stored in the storage unit 140. Thereafter, the process returns to step S301. Note that the timing for deleting the measurement data may be any timing as long as it is before the transition from the idle mode to the connected mode.

(4) Effects of the Embodiment As described above, according to the present embodiment, when the radio terminal UE configured to perform the Logged MDT detects a sudden decrease in the RSRP measurement value in the idle mode, the storage unit Control is performed to delete all the measurement data stored in 140.

  As a result, for example, the measurement data related to the coverage problem that the RSRP rapidly decreases when the radio terminal UE moves into the elevator and closes its door does not have to be reported to the E-UTRAN 10 when the mode is shifted to the connected mode. Thus, the coverage problem can be excluded from the network optimization target.

  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. This makes it possible to detect an abrupt decrease in the RSRP measurement value before the end of the recording period, thereby appropriately stopping measurement collection.

(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, measurement collection is started after the RSRP measurement value falls below the RSRP threshold A. However, measurement data before the RSRP measurement value falls below the RSRP threshold A needs to be reported to the E-UTRAN 10 as well. May perform measurement collection after step S301 and before step S305.

  In the above-described embodiment, measurement collection is stopped when the reception signal state is improved before the timeout. However, if the RSRP measurement value exceeds the RSRP threshold A before the internal timer value exceeds the internal timer threshold A, the measurement collection may be continued until a time-out occurs without ending the measurement collection immediately.

  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, SCBWTT is used as the recording condition. However, the recording condition is not limited to SCBWTT, and other recording conditions such as Periodic and Transmit power headroom becomes less than threshold may be used. Periodic is a recording condition in which recording is performed periodically, and Transmit power headroom becomes less than threshold is a recording condition in which recording is performed when the transmission power margin falls below the threshold.

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

  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 (5)

A storage unit;
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;
After recording measurement data including information on a received signal state measured by the measurement unit and position information at the time of measurement in the storage unit, the measurement data recorded in the storage unit is reported to the mobile communication network. And a control unit for controlling
The wireless terminal according to claim 1, wherein when the control unit detects a sudden change in a reception signal state measured by the measurement unit, the control unit controls to delete all measurement data recorded in the storage unit.   The wireless terminal according to claim 1, wherein the sudden change in the reception signal state is that a power level of a reception signal from the mobile communication network has decreased by a predetermined amount within a predetermined time. The control unit controls to record the measurement data in the storage unit according to a recording condition,
The recording condition is to perform recording over a certain period of time after the power level of the received signal falls below a threshold value,
The wireless terminal according to claim 2, wherein the predetermined time is shorter than the predetermined time.   The wireless terminal according to any one of claims 1 to 3, wherein the measurement of the reception signal state and the recording of the measurement data are performed in a state in which the wireless terminal is in a standby state. 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;
Recording measurement data including information on the received signal state measured in the measuring step and position information at the time of measurement in a storage unit;
And a step of deleting all measurement data recorded in the storage unit when the received signal state measured in the measuring step shows a sudden change.

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