WO2015072042A1

WO2015072042A1 - Radio terminal apparatus and reception quality reporting method

Info

Publication number: WO2015072042A1
Application number: PCT/JP2013/081077
Authority: WO
Inventors: 義博河▲崎▼; 田中　良紀; 好明太田
Original assignee: 富士通株式会社
Priority date: 2013-11-18
Filing date: 2013-11-18
Publication date: 2015-05-21

Abstract

A radio terminal apparatus comprises: a reception unit (201) that receives a radio signal; a determination unit (208) that determines whether the reception quality of the received signal, which was received by the reception unit, conforms to a charge reception quality the local apparatus has charge of reporting; and a transmission unit (212) that transmits a report signal when the determination unit determines that the reception quality of the received signal conforms to the charge reception quality.

Description

Wireless terminal apparatus and reception quality reporting method

The present invention relates to a wireless terminal device and a reception quality reporting method.

In recent years, for example, 3GPP (Third Generation Partnership Project), which is a standardization body for wireless communication systems such as LTE (Long Term Evolution), has developed specifications for LTE MBMS (Multimedia Broadcast and Multicast Service). MBMS is a service for simultaneously delivering multimedia data to a plurality of wireless terminal devices in a certain area using a common bearer. In the current MBMS specifications, the MBSFN (MBMS Single Frequency Network) system is adopted.

In the MBSFN system, a plurality of base station devices transmit the same signal simultaneously at the same frequency, and a radio terminal device in a cell under the control of each base station device transmits a signal transmitted from the plurality of base station devices wirelessly. This is a method for receiving a signal synthesized on a propagation path. At this time, since the distance between the wireless terminal device and each base station device is different, the signals transmitted from the respective base station devices reach the wireless terminal device at different timings. However, the radio terminal apparatus can receive a signal by the same operation as the reception process in a normal multipath environment by treating a signal arriving from a base station apparatus at a long distance as a delayed wave.

JP 2013-179666 A

By the way, in MBMS, since signals transmitted from a base station apparatus are received by a plurality of wireless terminal apparatuses, it is not easy to select an MCS (Modulation and Coding Scheme) in the base station apparatus. That is, in unicast communication in which a single wireless terminal device receives a signal, the base station device, for example, SIR (Signal to Signal) of a common reference signal (CRS: Cell-specific Reference Signal) unique to each base station device. A reception quality report such as (Interference Ratio) is received from the wireless terminal device, and an optimal modulation scheme and coding rate can be selected according to the reported reception quality. However, in MBMS, since the base station apparatus transmits the same signal to a plurality of radio terminal apparatuses having different reception qualities, it is difficult to select an optimal modulation scheme and coding rate when transmitting the signal. is there.

Specifically, since MBMS is a service that simultaneously distributes multimedia data to a plurality of wireless terminal devices, when the wireless terminal device also reports reception quality in MBMS, many wireless terminal devices At the same time, the reception quality is reported. As a result, the amount of traffic on the uplink radio channel from the radio terminal device to the base station device increases, interference increases, and the throughput of the entire radio communication system decreases. For this reason, it is not realistic that all wireless terminal devices that wish to receive multimedia data report reception quality.

For this reason, at present, 3GPP does not stipulate that a wireless terminal apparatus measures the reception quality of a reference signal related to MBMS data transmission and reports it to a base station apparatus in MBMS. Therefore, when realizing MBMS, it is conceivable to select a MCS with high error tolerance and transmit a signal from the base station apparatus so that a wireless terminal apparatus with low reception quality can receive multimedia data. That is, it is conceivable to reduce errors in a radio terminal apparatus with low reception quality by selecting a modulation method with a small number of bits that can be transmitted in one symbol or by selecting a coding rate that increases redundant bits. . As a result, multimedia data can be properly received in many wireless terminal devices, but it is difficult to improve the utilization efficiency of wireless resources, that is, the transmission efficiency.

Also, it is conceivable to determine the optimum MCS in each base station apparatus by actually measuring the reception quality of the reference signal related to the transmission of MBMS data at each location in the cell and collecting the measurement results. However, in this method, the actual measurement result of the reception quality is collected manually, which is inefficient and causes an increase in cost.

It should be noted that such a problem does not occur only when MBMS is performed, and can also occur, for example, in unicast communication. That is, for example, it may be preferable to grasp the current distribution of reception quality in a planning stage in which a new base station apparatus that covers an area with poor reception quality is arranged. In such a case, if each wireless terminal device reports reception quality, there is a problem that the amount of traffic on the uplink wireless line increases, and if actual measurement results are collected manually, there is a problem that costs increase. To do.

The disclosed technique has been made in view of the above points, and an object thereof is to provide a wireless terminal device and a reception quality reporting method capable of efficiently collecting reception quality.

The radio | wireless terminal apparatus which this application discloses WHEREIN: In one aspect, the receiving part which receives a radio signal, and the reception quality of the received signal received by the said receiving part correspond to the charge reception quality in charge of a self-apparatus And a determination unit that determines whether or not the reception quality of the received signal corresponds to the received reception quality by the determination unit, and a transmission unit that transmits a report signal.

According to one aspect of the wireless terminal device and reception quality reporting method disclosed in the present application, it is possible to efficiently collect reception quality.

1 is a diagram illustrating a configuration of a radio communication system according to Embodiment 1. FIG. FIG. 2 is a block diagram showing a configuration of the base station apparatus according to Embodiment 1. In FIG. FIG. 3 is a block diagram showing a configuration of the radio terminal apparatus according to Embodiment 1. In FIG. FIG. 4 is a diagram illustrating an example of a charge assignment table according to the first embodiment. FIG. 5 is a block diagram showing a configuration of a report determination unit according to Embodiment 1. FIG. 6 is a flowchart showing the operation of the wireless terminal device according to the first embodiment. FIG. 7 is a diagram illustrating an example of SIR distribution in a cell. FIG. 8 is a block diagram illustrating a configuration of a report determination unit according to the second embodiment. FIG. 9 is a flowchart showing the operation of the wireless terminal device according to the second embodiment. FIG. 10 is a diagram illustrating a hardware configuration example of the wireless terminal device.

Hereinafter, embodiments of a wireless terminal device and a reception quality reporting method disclosed in the present application will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment.

(Embodiment 1)
1 is a diagram illustrating a configuration of a radio communication system according to Embodiment 1. FIG. The wireless communication system illustrated in FIG. 1 includes a base station device 100 and a plurality of wireless terminal devices 200. Base station apparatus 100 performs radio communication with radio terminal apparatus 200 located in a subordinate cell. Further, base station apparatus 100 inserts a reference signal for reception quality measurement into a transmission signal and transmits it, and receives a report of the measurement result of the reception quality of the reference signal in radio terminal apparatus 200.

Although omitted in FIG. 1, a base station apparatus other than the base station apparatus 100 is also provided in the wireless communication system. When MBMS employing the MBSFN scheme is performed, signals having the same content addressed to a plurality of radio terminal apparatuses 200 are simultaneously transmitted from a plurality of base station apparatuses including the base station apparatus 100.

The plurality of radio terminal apparatuses 200 are located in a cell under the control of the base station apparatus 100, and each radio terminal apparatus 200 is assigned a range of reception quality in charge of reporting. That is, each wireless terminal device 200 measures the reception quality using the reference signal included in the received signal from the base station device 100, and when the measurement result of the reception quality corresponds to the received reception quality of the own device, Report data is transmitted to the station apparatus 100. Therefore, in this embodiment, not all wireless terminal devices 200 report reception quality, but only wireless terminal devices 200 whose reception quality measurement results correspond to their own reception quality transmit report data. To do.

As a result, it is possible to reduce the amount of traffic on the uplink radio channel from the radio terminal apparatus 200 to the base station apparatus 100, and to collect the reception quality in the cell without collecting the reception quality measurement result manually. Can do. Further, for example, even when a large number of wireless terminal devices 200 exist locally as in the area indicated by X in FIG. 1, some wireless terminal devices 200 transmit report data. It is possible to prevent excessive reception quality reporting.

FIG. 2 is a block diagram showing a configuration of base station apparatus 100 according to Embodiment 1. 2 includes an encoding unit 101, a modulation unit 102, a wireless transmission unit 103, a wireless reception unit 104, a demodulation unit 105, a decoding unit 106, and a totaling unit 107.

The encoding unit 101 encodes, for example, transmission data addressed to the wireless terminal device 200, control information related to reception quality reporting, and the like, and outputs the obtained encoded data to the modulation unit 102. At this time, the encoding unit 101 may perform encoding at a coding rate selected according to the reception quality tabulation result obtained by the tabulation unit 107 described later. Note that the transmission data addressed to the wireless terminal device 200 includes, for example, multimedia data distributed by MBMS. Further, the control information includes, for example, various initial setting information and information for instructing reception quality reporting. The control information may be stored in a MAC CE (MAC Control Element) that is a signal of a MAC (Media Access Control) layer, for example. The MAC CE is transmitted using PDSCH (Physical Downlink Shared Channel). Further, the control information may be directly transmitted by PDSCH or PDCCH (Physical Downlink Control Channel).

Modulation section 102 multiplexes and modulates the encoded data output from encoding section 101 and the reference signal for reception quality measurement, and outputs the obtained modulated signal to radio transmission section 103. At this time, the modulation unit 102 may perform modulation using a modulation method selected in accordance with the reception quality tabulation result obtained by the tabulation unit 107. The reference signal is a predetermined known signal that can be detected by the wireless terminal device 200. Also, a reference signal related to MBMS data transmission is called MBSFN RS (MBSFN Reference Signal) in the LTE specification, and is used for demodulation of a radio data signal in MBMS.

The wireless transmission unit 103 performs predetermined wireless transmission processing such as D / A (Digital / Analogue) conversion, frequency up-conversion, and power amplification on the modulated signal output from the modulation unit 102, and the obtained wireless signal is Transmit via antenna.

The radio reception unit 104 receives a radio signal transmitted from the radio terminal device 200 via an antenna, and performs predetermined radio reception processing such as frequency down-conversion and A / D (Analogue / Digital) conversion on the received signal. The received signal is output to the demodulator 105. Note that this received signal includes, for example, report data transmitted from the wireless terminal device 200 whose reception quality is measured.

Demodulation section 105 demodulates the received signal output from radio reception section 104 and outputs the obtained demodulated signal to decoding section 106.

The decoding unit 106 decodes the demodulated signal output from the demodulation unit 105, and outputs the obtained decoded data to the totaling unit 107. At this time, the decoding unit 106 outputs, among the decoded data, report data transmitted from the wireless terminal device 200 to the counting unit 107 in particular.

The totaling unit 107 acquires the report data output from the decoding unit 106, and totals the reception quality in the cell under the base station apparatus 100. That is, the totaling unit 107 uses the report data from the wireless terminal device 200 to acquire the reception quality distribution at various locations in the cell. The detailed analysis of the reception quality in the cell may be performed by another device that is directly or indirectly connected to the base station device 100.

FIG. 3 is a block diagram showing a configuration of radio terminal apparatus 200 according to Embodiment 1. 3 includes a radio reception unit 201, a demodulation unit 202, a decoding unit 203, an SIR measurement unit 204, a buffer unit 205, a position measurement unit 206, a table storage unit 207, a report determination unit 208, and transmission data generation. Unit 209, encoding unit 210, modulation unit 211, and wireless transmission unit 212.

Radio receiving section 201 receives a radio signal transmitted from base station apparatus 100 via an antenna, and performs predetermined radio reception processing such as frequency down-conversion and A / D conversion on the received signal. The received signal is output to demodulation section 202. Note that this received signal includes, for example, the above-described multimedia data, control information, reference signal, and the like. As described above, MBSFN RS is used as a reference signal in LTE-compliant MBMS. Also, for example, in the radio terminal apparatus 200 corresponding to MBMS adopting the MBSFN scheme, the radio reception unit 201 uses a radio signal obtained by combining signals transmitted from a plurality of base station apparatuses including the base station apparatus 100 as an antenna. Receive via.

The demodulation unit 202 demodulates the reception signal output from the wireless reception unit 201 and outputs the obtained demodulation signal to the decoding unit 203.

The decoding unit 203 decodes the demodulated signal output from the demodulation unit 202 to obtain decoded data. Decoding section 203 then outputs control information relating to the report of reception quality, among the obtained decoded data, to report determination section 208.

The SIR measurement unit 204 measures the SIR using a known reference signal included in the demodulated signal obtained by the demodulation unit 202. That is, the SIR measurement unit 204 measures reception quality in the wireless terminal device 200. When the received signal is an MBMS signal, SIR measurement section 204 uses MBSFN RS to receive a signal obtained by combining signals transmitted from a plurality of base station apparatuses including base station apparatus 100. Measure reception quality. In this case, the SIR measurement unit 204 may measure not only the MBSFN RS reception quality but also the CRS reception quality specific to each base station apparatus.

The buffer unit 205 temporarily stores the SIR measurement value measured by the SIR measurement unit 204.

The position measuring unit 206 includes, for example, a GPS (Global Positioning System) receiver and acquires position information of the wireless terminal device 200. Note that the position measurement unit 206 does not necessarily include a GPS receiver, and may acquire position information through measurement using, for example, PRS (Positioning Reference Signal) transmitted from a plurality of base station apparatuses. .

The table storage unit 207 stores a responsible assignment table that indicates the correspondence between the index of each wireless terminal device 200 and the SIR that each wireless terminal device 200 is responsible for reporting. Specifically, the table storage unit 207 stores, for example, a charge assignment table as shown in FIG. This assigned allocation table stores N indexes (N is a positive integer) and associated SIRs indicating the range of SIRs to which the wireless terminal device 200 to which each index is assigned is responsible for reporting. That is, in the assigned assignment table shown in FIG. 4, for example, the assigned SIR of the wireless terminal device 200 to which the index “0” is assigned is “−10 to −5.1 dB (decibel)”, and the assigned index “3” is given. The assigned SIR of the wireless terminal device 200 is “5 to 9.9 dB”.

Here, the index may be assigned to each wireless terminal device 200 in advance, or may be notified to each wireless terminal device 200 by control information transmitted from the base station device 100. Furthermore, since a unique identification number is assigned to each wireless terminal device 200, an index obtained from this identification number may be assigned to each wireless terminal device 200. Specifically, for example, the identification number (C-RNTI: Cell Radio Network Temporary Identifier) assigned by the base station device 100 when the wireless terminal device 200 is located in the cell of the base station device 100 is the total number N of indexes. The remainder after division may be used as an index of the wireless terminal device 200. Further, the remainder obtained by dividing the identification number unique to the wireless terminal device 200 by the total number N of indexes may be used as the index of the wireless terminal device 200.

Returning to FIG. 3, the report determination unit 208 determines whether the report determination unit 208 is based on the control information output from the decoding unit 203, the SIR measurement value held in the buffer unit 205, and the assigned allocation table stored in the table storage unit 207. It is determined whether or not the device reports on reception quality. Specifically, the report determination unit 208 confirms the index assigned to the own device, and acquires the assigned SIR of the own device from the assigned assignment table stored in the table storage unit 207. That is, the report determination unit 208 acquires the assigned SIR corresponding to the index of the own device from the assigned assignment table.

Then, when the control information for instructing the reception quality report is received, the report determination unit 208 determines whether or not the SIR measurement value held in the buffer unit 205 corresponds to the assigned SIR of the own device. As a result of this determination, when the SIR measurement value corresponds to the SIR in charge of the own device, the report determination unit 208 generates report data including the position information acquired by the position measurement unit 206, and transmits the transmission data generation unit 209. Output to. On the other hand, when the SIR measurement value does not correspond to the assigned SIR of the own device, the report determination unit 208 does not generate report data. The report data may include not only information related to SIR measurement results but also other information. In addition, for example, when reporting is performed at short time intervals, it is considered that the position information does not change greatly, and therefore report data not including the position information may be generated. The detailed configuration of the report determination unit 208 will be described later with reference to FIG.

The transmission data generation unit 209 generates transmission data including user information and control information addressed to the base station apparatus 100 and report data output from the report determination unit 208. The transmission data generation unit 209 may generate transmission data that does not include report data when report data is not output from the report determination unit 208. Further, the transmission data generation unit 209 may generate transmission data by arranging report data in a data channel (for example, PUSCH: Physical Uplink Shared Channel) for transmitting user information, or to transmit control information. The transmission data may be generated by arranging report data in a control channel (for example, PUCCH: Physical Uplink Control Channel). Further, for example, report data may be stored in a MAC CE which is a MAC layer signal, and the MAC CE may be transmitted using a data channel.

The encoding unit 210 encodes the transmission data generated by the transmission data generation unit 209 and outputs the obtained encoded data to the modulation unit 211.

Modulation section 211 modulates the encoded data output from encoding section 210 and outputs the obtained modulated signal to radio transmission section 212.

The radio transmission unit 212 performs predetermined radio transmission processing such as D / A conversion, frequency up-conversion, and power amplification on the modulated signal output from the modulation unit 211, and transmits the obtained radio signal via an antenna. To do.

Next, the configuration of the report determination unit 208 according to Embodiment 1 will be described with reference to FIG. The report determination unit 208 illustrated in FIG. 5 includes a control information acquisition unit 208a, an SIR determination unit 208b, and a report data generation unit 208c.

The control information acquisition unit 208a acquires control information related to the report of reception quality, among the decoded data obtained by the decoding unit 203. Specifically, the control information acquisition unit 208a, for example, at the time of initial setting for starting communication with the base station apparatus 100, information for specifying a subframe including a reference signal among a plurality of subframes constituting a received signal, Information on an index assigned to the wireless terminal device 200 is acquired. In addition, the control information acquisition unit 208a acquires control information that instructs reception quality reporting.

The SIR determination unit 208b acquires and holds an index assigned to the wireless terminal device 200 from the control information acquired by the control information acquisition unit 208a. Specifically, the SIR determination unit 208b acquires and holds an index assigned to the own device by the base station device 100, for example, from the control information. Further, the SIR determination unit 208b may acquire a rule for obtaining an index from an identification number unique to the wireless terminal device 200 from the control information, for example, and obtain and hold an index assigned to the own device according to the obtained rule. . The rule for obtaining the index may be determined in advance instead of being acquired from the control information. Further, the index may be obtained according to a rule corresponding to an identification number (C-RNTI) assigned by base station apparatus 100 while radio terminal apparatus 200 is in the cell of base station apparatus 100.

Then, the SIR determination unit 208b acquires the assigned SIR range corresponding to the index assigned to the own apparatus from the assigned assignment table stored by the table storage unit 207. That is, for example, when the assigned allocation table shown in FIG. 4 is stored in the table storage unit 207 and the index assigned to the own apparatus is “0”, the SIR determination unit 208b sets the assigned SIR range as “ -10 to -5.1 dB "is acquired.

Then, when the control information acquisition unit 208a acquires the control information for instructing the reception quality report, the SIR determination unit 208b acquires the SIR measurement value held in the buffer unit 205, and the SIR measurement value is It is determined whether it corresponds to the SIR in charge. That is, for example, when the SIR range of the own apparatus is “−10 to −5.1 dB”, it is determined whether or not the SIR measurement value is a value included in this range. As a result of the determination, if the SIR measurement value corresponds to the SIR in charge of the own device, the SIR determination unit 208b instructs the report data generation unit 208c to generate report data.

When the report data generation unit 208c is instructed to generate the report data from the SIR determination unit 208b, the report data generation unit 208c acquires the position information from the position measurement unit 206, and reports the report data including the position information and an identification number unique to the own device. Generate. At this time, the report data generation unit 208c may generate report data including SIR measurement values, but may generate report data not including SIR measurement values. Even when the report data does not include the SIR measurement value, since the index assigned to the wireless terminal device 200 can be specified from the identification number included in the report data, the SIR in charge of the wireless terminal device 200 is specified. Therefore, the SIR in charge of the wireless terminal device 200 is specified also by the report data not including the SIR measurement value, and the base station device 100 is informed that the SIR measurement value in the wireless terminal device 200 is a value included in the range of the assigned SIR. It is possible to report. In addition, when the radio resource of the uplink radio channel used by the radio terminal device 200 for reporting the measurement result is allocated by the base station device 100, the base station device 100 specifies the radio terminal device 200 that performs the report. Therefore, an identification number unique to the apparatus may not be included in the report data.

Next, the reception quality reporting method in radio terminal apparatus 200 configured as described above will be described with reference to the flowchart shown in FIG.

First, the wireless terminal device 200 performs initial setting for reception quality reporting. Specifically, the SIR measurement unit 204 sets a subframe including a reference signal among a plurality of subframes constituting the received signal as a measurement target subframe (step S101). That is, one frame of the received signal is composed of, for example, 10 subframes. When the reference signal is included in the second subframe among these subframes, for example, the second subframe is the measurement target. Set to subframe. With this setting, the SIR measurement unit 204 measures the SIR using the reference signal included in the second subframe of the received signal at the time of SIR measurement. Note that the subframe including the reference signal may be notified from the base station apparatus 100 using the control information, or may be determined in advance. In the LTE specification, information indicating which subframe is used for MBMS data transmission is periodically broadcast from each base station apparatus.

Also, a responsible allocation table indicating the correspondence between the index and the responsible SIR range is set in the table storage unit 207 (step S102). The assigned allocation table may be notified from the base station apparatus 100 using control information, or may be stored in the table storage unit 207 in advance.

Furthermore, the index of the own device is set in the SIR determination unit 208b of the report determination unit 208 (step S103). The index of each radio terminal apparatus 200 may be notified from the base station apparatus 100 using control information, and is calculated from an identification number unique to each radio terminal apparatus 200 and a C-RNTI assigned by the base station apparatus 100. May be. When calculating the index from the identification number, for example, the remainder obtained by dividing the identification number by the total number of indexes can be used as the index.

When the initial setting is completed and a signal is received by the wireless reception unit 201 (step S104), the received signal is demodulated by the demodulation unit 202. Then, the SIR measurement unit 204 uses the reference signal included in the set measurement target subframe to measure the SIR of the received signal (step S105). The measured SIR measurement value is temporarily held in the buffer unit 205.

Then, the demodulated signal obtained by the demodulating unit 202 is decoded by the decoding unit 203 to obtain decoded data. Control information related to the report of reception quality in the decoded data is acquired by the control information acquisition unit 208a. Specifically, control information for instructing reception quality reporting is acquired by the control information acquisition unit 208a (step S106).

When the control information is acquired by the control information acquisition unit 208a, the SIR determination unit 208b acquires the assigned SIR corresponding to the index of the own apparatus from the assigned assignment table stored in the table storage unit 207. Then, the SIR determination unit 208b compares the SIR measurement value held in the buffer unit 205 with the assigned SIR, thereby determining whether or not the SIR measurement value corresponds to the assigned SIR (step S107).

As a result of this determination, when the SIR measurement value does not correspond to the assigned SIR (No in step S107), the reception quality from the wireless terminal device 200 is not reported. For this reason, the radio terminal apparatus 200 whose SIR measurement value does not correspond to the assigned SIR does not transmit report data and does not use resources of the uplink radio channel.

On the other hand, when the SIR measurement value corresponds to the responsible SIR (step S107 Yes), report data is generated by the report data generation unit 208c (step S108). Specifically, report data including the position information of the own device obtained by the position measuring unit 206 and an identification number unique to the own device is generated. At this time, the report data generation unit 208c may or may not include the SIR measurement value in the report data. When the SIR measurement value is included in the report data, accurate reception quality can be reported by the report data. On the other hand, when the SIR measurement value is not included in the report data, the index of the own apparatus and the assigned SIR can be specified from the identification number included in the report data. Then, the base station apparatus 100 that receives the report data can grasp from the charge SIR and the position information that the SIR at the position indicated by the position information corresponds to the charge SIR.

The generated report data is multiplexed with user information or control information by the transmission data generation unit 209 as necessary, and transmission data including the report data is generated. The transmission data may include only report data and control information related to the report data. The transmission data is encoded by the encoding unit 210, modulated by the modulation unit 211, and then transmitted from the wireless transmission unit 212 to the base station apparatus 100 (step S109).

The radio resource of the uplink radio channel for transmitting the transmission signal including the report data is, for example, as a result of the radio terminal device 200 requesting the uplink radio channel resource to the base station device 100, so that the base station device 100 can It may be assigned to the device 200. By doing so, each wireless terminal device 200 transmits report data at different timings, and interference can be reduced. The request for the radio resource of the uplink radio channel is performed using, for example, an SR (Scheduling Request) or a random access signal, and the notification of the radio resource allocation content by the base station apparatus 100 is transmitted using, for example, PDCCH / EPDCCH. UL grant may be used.

In the base station apparatus 100 that receives a signal including report data, the totaling unit 107 totals reception quality. That is, report data is acquired from a plurality of wireless terminal devices 200, and position information included in the report data is associated with reception quality information. As a result, the base station apparatus 100 can grasp the distribution of reception quality in the cell as shown in FIG. 7, for example. When the reception quality distribution shown in FIG. 7 is obtained, for example, a new base station device is installed at point A in FIG. 7 to improve the reception quality in the area not covered by the base station device 100. Etc. can be considered. The totaling unit 107 performs some processing such as blocking the collected data, and analyzes the collected data by another device directly or indirectly connected to the base station device 100. May be done.

Also, if the distribution of reception quality within a cell can be grasped, for example, when implementing MBMS, it becomes easy to select an optimal MCS. That is, it is possible to select a modulation scheme and a coding rate according to reception quality in a cell without selecting a modulation scheme and a coding rate with excessively low transmission efficiency. In addition, the transmission power can be easily adjusted in each base station apparatus that transmits the MBMS data signal. In this embodiment, not all wireless terminal devices 200 report reception quality, but only wireless terminal devices 200 whose SIR measurement values correspond to their assigned SIRs transmit report data. For this reason, it is possible to suppress an increase in traffic volume and an increase in interference on the uplink radio channel.

As described above, according to the present embodiment, a responsible SIR in charge of reporting is assigned to each of a plurality of wireless terminal devices, and each wireless terminal device has an SIR measurement value corresponding to its own device SIR. Only when the report data of the reception quality is transmitted. For this reason, even if the actual measurement results are not collected manually, efficient reception quality can be collected while suppressing the amount of traffic on the uplink radio channel from the radio terminal device to the base station device.

(Embodiment 2)
The feature of Embodiment 2 is that the index assigned to each wireless terminal device is not a fixed index but a variable index.

Since the configurations of the radio communication system, the base station apparatus, and the radio terminal apparatus according to Embodiment 2 are the same as those in Embodiment 1 (FIGS. 1 to 3), description thereof is omitted. In the second embodiment, the configuration of the report determination unit 208 of the wireless terminal device 200 is different from that of the first embodiment.

FIG. 8 is a block diagram illustrating a configuration of the report determination unit 208 according to the second embodiment. 8, the same parts as those in FIG. 5 are denoted by the same reference numerals, and the description thereof is omitted.

The index calculation unit 208d calculates an index to be given to the wireless terminal device 200 when the control information instructing the reception quality report is acquired by the report information acquisition unit 208a. Specifically, the index calculation unit 208d adds a predetermined value to the current index every time control information is acquired, for example, to obtain a new index. That is, the index calculation unit 208d changes the index assigned to the own device by accumulating a predetermined value to a predetermined initial value for each wireless terminal device 200. If the index value exceeds the maximum index value as a result of adding the predetermined value, the index calculation unit 208d may set the index to a predetermined initial value again.

Also, the index calculation unit 208d may calculate the index given to the own device using the number of the subframe including the control information or the number of the slot constituting the subframe including the control information. Specifically, the index calculation unit 208d adds, for example, a subframe number including control information to a predetermined initial value for each wireless terminal device 200, and a remainder obtained by dividing the obtained sum by the total number of indexes. Is calculated as an index. Thus, if the base station apparatus 100 changes the number of the subframe storing the control information for instructing the reception quality report, the index assigned to each wireless terminal apparatus 200 is changed in accordance with this change. .

In this embodiment, the index calculation unit 208d calculates the index assigned to the own device, so that the index changes every time reception quality is reported. Therefore, when the SIR determination unit 208b acquires the assigned SIR corresponding to the index from the assigned assignment table, the assigned SIR that is acquired every time the reception quality is reported changes. As a result, for example, even when the wireless terminal device 200 is stopped at the same position and the SIR measurement value does not change, it is possible to avoid the reception quality report from the wireless terminal device 200 not being performed. For this reason, the base station apparatus 100 uniformly collects information regarding reception quality in the cell, and an accurate distribution of reception quality can be acquired.

Next, the reception quality reporting method according to Embodiment 2 will be described with reference to the flowchart shown in FIG. 9, the same parts as those in FIG. 6 are denoted by the same reference numerals, and detailed description thereof is omitted. In FIG. 9, step S103 of FIG. 6 is deleted, and step S201 is added.

Also in the second embodiment, as in the first embodiment, the wireless terminal device 200 performs initial setting for reception quality reporting. That is, the SIR measurement unit 204 sets the subframe including the reference signal as the measurement target subframe (step S101), and sets the assigned allocation table in the table storage unit 207 (step S102).

When such initial setting is completed and a signal is received by the wireless reception unit 201 (step S104), the SIR measurement unit 204 measures the SIR of the received signal (step S105). The measured SIR measurement value is temporarily held in the buffer unit 205.

Further, the received signal is decoded by the decoding unit 203 to obtain decoded data. Control information related to the report of reception quality in the decoded data is acquired by the control information acquisition unit 208a. Specifically, control information for instructing reception quality reporting is acquired by the control information acquisition unit 208a (step S106).

When the control information is acquired by the control information acquisition unit 208a, the index given to the own device is calculated by the index calculation unit 208d (step S201). Specifically, for example, a new index is calculated by adding a predetermined value to the current index. Further, for example, a remainder obtained by dividing the sum of the subframe number including the control information and the predetermined initial value for each wireless terminal device 200 by the total number of indexes may be used as a new index.

The calculated index is notified to the SIR determination unit 208b, and the SIR determination unit 208b acquires the assigned SIR corresponding to the index from the assigned allocation table. Then, the SIR determination unit 208b compares the SIR measurement value held in the buffer unit 205 with the assigned SIR, thereby determining whether or not the SIR measurement value corresponds to the assigned SIR (step S107).

On the other hand, when the SIR measurement value corresponds to the responsible SIR (step S107 Yes), report data is generated by the report data generation unit 208c (step S108). The generated report data is multiplexed with user information or control information by the transmission data generation unit 209 as necessary, and transmission data including the report data is generated. The transmission data may include only report data and information related to the report data. The transmission data is encoded by the encoding unit 210, modulated by the modulation unit 211, and then transmitted from the wireless transmission unit 212 to the base station apparatus 100 (step S109).

As described above, according to the present embodiment, the index assigned to the wireless terminal device is changed to change the assigned SIR to which each wireless terminal device is responsible for reporting, and the SIR measurement value is the assigned SIR of the own device. Only when the above is true, the reception quality report data is transmitted. For this reason, even if the actual measurement results are not collected manually, efficient reception quality can be collected while suppressing the amount of traffic on the uplink radio channel from the radio terminal device to the base station device. Also, since the assigned SIR changes, it is possible to avoid that the wireless terminal device always reports or does not always report the reception quality even if the SIR measurement value of the wireless terminal device does not change. As a result, the distribution of reception quality within the cell can be obtained uniformly in the base station apparatus.

Note that it is also possible to create a program in which the reception quality report processing executed by the wireless terminal device according to each of the above embodiments is described in a language that can be executed by a computer. In this case, the same effect as that of each of the above-described embodiments can be obtained by the computer installed in the wireless terminal device executing the program. Furthermore, by recording the above-described program on a computer-readable recording medium, and reading and executing the program recorded on the recording medium, a reception quality reporting process similar to that in each of the above embodiments is realized. May be.

FIG. 10 is a block diagram showing a hardware configuration of a wireless terminal device 300 equipped with a computer that executes the above program. As shown in FIG. 10, a wireless terminal device 300 includes a CPU (Central Processing Unit) 310 that executes the above program, an input unit 320 that inputs data, a ROM (Read Only Memory) 330 that stores various data, an operation parameter, and the like. A RAM (Random Access Memory) 240, a reading unit 350 that reads the program from the recording medium 400 on which the program is recorded, an output unit 360 such as a display, and a wireless interface 370 that transmits and receives signals via an antenna. , Connected by a bus 380.

The CPU 310 reads the program recorded on the recording medium 400 via the reading unit 350 and then executes the program to realize reception quality report processing. That is, the CPU 310 performs the demodulation unit 202, the decoding unit 203, the SIR measurement unit 204, the buffer unit 205, the report determination unit 208, the transmission data generation unit 209, the encoding unit 210, and the modulation unit of the wireless terminal device 200 illustrated in FIG. The process according to 211 is executed. At this time, the CPU 310 refers to the assigned allocation table stored in the RAM 340 corresponding to the table storage unit 207 shown in FIG.

Note that examples of the recording medium 400 include a flash memory, an optical disk, a flexible disk, a CD-ROM, and a hard disk. In addition, this program may be introduced into the wireless terminal device 300 via wireless communication using the wireless interface 370 or may be introduced into the wireless terminal device 300 via wired communication using an interface (not shown).

DESCRIPTION OF SYMBOLS 100 Base station apparatus 101 Encoding part 102 Modulation part 103 Wireless transmission part 104 Wireless reception part 105 Demodulation part 106 Decoding part 107 Aggregation part 200 Wireless terminal apparatus 201 Radio reception part 202 Demodulation part 203 Decoding part 204 SIR measurement part 205 Buffer part 206 Position measurement unit 207 Table storage unit 208 Report determination unit 208a Control information acquisition unit 208b SIR determination unit 208c Report data generation unit 208d Index calculation unit 209 Transmission data generation unit 210 Encoding unit 211 Modulation unit 212 Wireless transmission unit

Claims

A receiver for receiving a radio signal;
A determination unit that determines whether or not the reception quality of the reception signal received by the reception unit corresponds to the received reception quality for which the device is in charge of reporting;
A wireless terminal apparatus comprising: a transmission unit that transmits a report signal when the determination unit determines that the reception quality of the received signal corresponds to the assigned reception quality.
The wireless terminal device according to claim 1, wherein the transmission unit transmits a report signal including at least position information of the device itself.
The wireless terminal device according to claim 1, wherein the transmission unit transmits a report signal including at least position information of the device itself and measured reception quality.
A storage unit that associates and stores an index assigned to each of the plurality of wireless terminal devices and a range of reception quality in charge of reporting for each index;
The determination unit
A range of reception quality corresponding to the index of the own device is acquired from the storage unit, and it is determined whether or not the measured reception quality measured for the received signal is included in the acquired reception quality range. The wireless terminal device according to claim 1.
The determination unit
The radio terminal apparatus according to claim 4, wherein an index assigned to the own apparatus by the base station apparatus is acquired, and a range of reception quality corresponding to the acquired index is acquired from the storage unit.
The determination unit
The wireless terminal apparatus according to claim 4, wherein an index assigned to the own apparatus is obtained from identification information unique to the own apparatus, and a range of reception quality corresponding to the obtained index is obtained from the storage unit.
The determination unit
5. The index of the own apparatus is changed each time control information instructing reporting of reception quality is received, and a range of reception quality corresponding to the index after the change is acquired from the storage unit. Wireless terminal device.
The determination unit
Of the plurality of subframes constituting the received signal, the index of the own apparatus is determined according to the position of the subframe including the control information instructing the report of the reception quality, and the range of the reception quality corresponding to the determined index The wireless terminal device according to claim 4, wherein the wireless terminal device is acquired from the storage unit.
The receiver is
The radio terminal apparatus according to claim 1, wherein a radio signal obtained by combining signals transmitted simultaneously from a plurality of base station apparatuses on a radio propagation path is received.
The wireless terminal device according to claim 1, wherein the receiving unit receives an MBSFN RS (MBMS Single Frequency Network Reference Signal) used in MBMS (Multimedia Broadcast and Multicast Service).
A base station apparatus, comprising: a reception unit configured to receive a report signal transmitted from a radio terminal apparatus whose reception quality measured by the radio terminal apparatus corresponds to the reception quality assigned in advance to the radio terminal apparatus.
The base station apparatus according to claim 11, wherein the receiving unit receives a report signal including at least position information of the wireless terminal apparatus.
The base station apparatus according to claim 11, wherein the receiving unit receives a report signal including at least position information of the wireless terminal apparatus and reception quality measured by the wireless terminal apparatus.
The base station apparatus according to claim 11, further comprising a totaling unit that counts reception quality in the cell of the own apparatus using the report signal received by the receiving unit.
A transmission unit for determining a coding rate or a modulation method to be applied to a transmission signal based on a totaling result obtained by the aggregation unit, and transmitting a signal encoded or modulated by the determined coding rate or modulation method; The base station apparatus according to claim 14, comprising:
A reception quality reporting method executed by a wireless terminal device, comprising:
Receive radio signals,
Measure the reception quality of the received signal received,
It is determined whether the measured measurement reception quality corresponds to the reception quality in charge for which the wireless terminal device is in charge of reporting,
A reception quality reporting method comprising: a process of transmitting a report signal including position information of the wireless terminal device when it is determined that the measured reception quality corresponds to the assigned reception quality.