JP5719250B2 - Wireless base station and wireless communication method - Google Patents

Description

  The present invention relates to a radio base station and a radio communication method.

  In LTE, in order to effectively perform scheduling of a communication device (UE: User Equipment) of each user, channel quality of an uplink (Up Link) is estimated over the entire frequency band in the system for each communication device. . Specifically, each communication device transmits a known reference signal SRS (Sounding Reference Signal) to the radio base station, and the radio base station detects the SRS and estimates the uplink channel quality for each communication device. (For example, Non-Patent Document 1). In particular, a frequency band that has not been allocated as a data channel (PUSCH: Physical Up Shared Channel) in the past, or a channel that has been allocated to a data channel in the past, but the channel quality fluctuates after a long time since allocation For frequency bands that are likely to be used, the importance of estimating channel quality by SRS detection is high.

  In addition, for detection of SRS, inverse characteristic multiplication, IDFT (Inverse Discrete Fourier Transform) processing, user retrieval, DFT (Discrete Fourier Transform) processing, channel equalization processing, SINR (Signal to Interface Ratio processing required) (For example, Non-Patent Document 2).

Takeshi Hattori, Tomoo Morohashi, Masanobu Fujioka, “All of 3G Evolution LTE Mobile Broadband Technology”, Maruzen, 2009, p. 438 Motoya Iwasaki, “Towards the realization of LTE and further leap forward”, NEC, [online], [Search May 19, 2011], Internet <http://www.mcrg.ee.titech.ac.jp/OH2009Lectures /OH09_lecture_Iwasaki.pdf>

  FIG. 6 shows an operation related to channel quality estimation processing based on SRS detection of a conventional radio base station. As shown in FIG. 6, a conventional radio base station first receives an SRS from one or more communication devices connected to the radio base station (step S101). Subsequently, the conventional radio base station performs SRS detection processing of all communication apparatuses that have transmitted SRS, and performs channel quality estimation processing (step S102).

  Here, the maximum number of communication devices that can transmit SRS is 192 in the case of the 10 MHz band. However, when the radio base station detects all SRSs transmitted by the communication device 192, the load for detecting SRSs is larger than the data channel decode load, and the data channel decodes. There are adverse effects such as processing delay.

  On the other hand, there is a method in which the radio base station assigns the communication devices so that the SRS can be transmitted only to a number of communication devices that can be calculated by the radio base station. In this case, the channel quality of all the communication devices is estimated. In particular, it becomes difficult to estimate channel quality in real time for each communication device.

  Therefore, the object of the present invention made in view of the above problems is to increase the load for detecting SRS as compared with the decoding load of the data channel, and to a more important data channel decoding process. An object of the present invention is to provide a radio base station and a radio communication method capable of reducing the influence and estimating the real-time channel quality.

In order to solve the above problems, a radio base station according to the present invention provides:
A control unit that performs estimation processing for estimating wireless communication quality with the communication device based on known signals received from one or more communication devices, and decoding processing of a data channel received from the communication device;
The controller is
When the sum of the processing amount required for the estimation process and the processing amount required for the decoding process is greater than or equal to a predetermined threshold for all of the known signals from one or more communication devices, the processing amount required for the decoding process is The estimation process is performed only for a part of the known signals from one or more communication devices without reduction.

The radio base station according to the present invention is
From the one or more communication devices, the control unit is based on a calculation resource necessary for performing the estimation process and a calculation resource necessary for the decoding process for all of the known signals received from the one or more communication devices. It is characterized in that it is determined whether or not the estimation process can be performed for all the received known signals without reducing the processing amount required for the decoding process.

The radio base station according to the present invention is
A priority is set for each of the one or more communication devices that transmit the known signal, and the estimation process is performed on the known signal transmitted by the communication device having the priority equal to or higher than a predetermined value.

The radio base station according to the present invention is
The control unit determines the priority based on a detection frequency of the known signal transmitted by the communication device.

The radio base station according to the present invention is
The control unit determines the priority based on a fluctuation value of channel quality of the communication device.

The radio base station according to the present invention is
The control unit determines the priority based on a signal level of the known signal transmitted by the communication device.

The wireless communication method according to the present invention includes:
Including a control step of performing estimation processing for estimating wireless communication quality with the communication device based on a known signal received from the communication device, and composite processing of a data channel received from the communication device,
The control step includes
When the sum of the processing amount required for the estimation process and the processing amount required for the decoding process is greater than or equal to a predetermined threshold for all of the known signals from one or more communication devices, the processing amount required for the decoding process is The estimation process is performed only for a part of the known signals from one or more communication devices without reduction.

  According to the radio base station and radio communication method of the present invention, it is possible to reduce the influence on the decoding process of the more important data channel without increasing the load for detecting the SRS as compared with the decoding load of the data channel, In addition, real-time channel quality can be estimated.

2 is a block diagram of a radio base station according to Embodiment 1. FIG. It is the information stored in the memory | storage part of the wireless base station of Embodiment 1. FIG. 3 is a flowchart illustrating an operation of the radio base station according to the first embodiment. 6 is a block diagram of a radio base station according to Embodiment 2. FIG. 6 is a flowchart illustrating an operation of the radio base station according to the second embodiment. It is a flowchart showing operation | movement of the wireless base station in a prior art.

  Embodiments of the present invention will be described below.

(Embodiment 1)
FIG. 1 is a block diagram of a radio base station according to Embodiment 1 of the present invention. The radio base station 1 according to an embodiment of the present invention includes a receiving unit 11, a control unit 12, and a storage unit 13.

  The receiving unit 11 receives SRS from one or more communication devices connected to the radio base station 1. SRS is a known signal for estimating channel quality (wireless communication quality) with a communication device. The receiving unit 11 receives the SRS in all frequency bands that can be used for wireless communication.

  The control unit 12 detects the processing load of processing in the radio base station 1. Specifically, the control unit 12 performs a decoding process on the data channel received from the communication apparatus and a decoding process on the uplink control channel (PUCCH: Physical Uplink Control Channel). Further, the control unit 12 detects the total value of the processing loads of the processes being executed in the CPU of the radio base station 1. The processing in the radio base station 1 includes data channel decoding processing, uplink control channel decoding processing, and the like. Furthermore, the control part 12 calculates the calculation resource for SRS detection which can be used for SRS detection based on the total value of the detected processing load. The calculation resource is calculated by subtracting the total value of the processing loads from the maximum processing amount that can be processed by the radio base station 1.

  In addition, the control unit 12 compares the SRS received from one or more communication devices with the calculation resource for SRS detection. Then, the control unit 12 determines whether or not calculation resources for SRS detection are sufficient, that is, whether or not all of the SRSs received by the calculation resource for SRS detection can be detected. When the calculation resource for SRS detection is not sufficient, the sum of the processing amount required for estimation processing based on detection of all SRSs received from one or more communication devices and the processing amount required for data channel decoding processing is , It means a case where it is equal to or greater than a predetermined threshold.

  In other words, the control unit 12 uses all of the received SRSs based on the calculation resources necessary for performing the SRS detection process and the calculation resources necessary for the data channel decoding process for all of the SRSs received from the one or more communication devices. It is determined whether or not it is possible to perform channel estimation processing. When the calculation resource for SRS detection is sufficient, the control part 12 performs the received SRS detection process, and performs the channel quality estimation process. On the other hand, when the calculation resources for SRS detection are not sufficient, the control unit 12 reduces the processing amount required for SRS detection without reducing the processing amount required for the data channel decoding processing, and only for some communication devices. SRS detection processing is performed. Specifically, the control unit 12 sets the priority of each communication device related to detection of the received SRS, performs SRS detection processing based on the priority, and performs channel quality estimation processing.

  The control unit 12 calculates priority according to various criteria. The priority for SRS detection is determined for each communication device on the basis of past SRS detection frequency, standard deviation of channel quality, or SRS signal strength (RSSI: Received Signal Strength Indication). The control unit 12 uses any one of the three criteria as a priority calculation criterion. As will be described later, the control unit 12 may calculate the priority by combining some or all of the three criteria.

  The standard concerning the detection frequency of SRS is a standard that determines the priority according to the frequency of detecting the SRS transmitted by each communication device in the past. Specifically, when the detection frequency of the SRS stored in the storage unit 13 is less than the first threshold, the time has elapsed since the SRS was detected in the past, and the uplink channel of the frequency band Since there is a high possibility that the quality has fluctuated, the control unit 12 sets the priority to 1 in this case. On the other hand, when the detection frequency of the SRS stored in the storage unit 13 is equal to or higher than the first threshold, the time has not elapsed since the SRS was detected in the past, and the uplink channel quality of the frequency band Therefore, the control unit 12 sets the priority to 0 in this case.

  Further, the standard relating to the standard deviation of the channel quality is a standard for determining the priority according to the standard deviation of the channel quality estimated by the radio base station 1 in the past. Specifically, when the standard deviation of the channel quality of each communication device stored in the storage unit 13 is greater than or equal to the second threshold value, there is a high possibility that the uplink channel quality of the frequency band has changed. In this case, the control unit 12 sets the priority to 1. On the other hand, when the standard deviation of the channel quality of each communication device stored in the storage unit 13 is less than the second threshold, it is unlikely that the uplink channel quality of the frequency band has changed. In this case, the control unit 12 sets the priority to 0.

  Moreover, the reference | standard concerning the signal strength of SRS is a reference | standard which determines a priority according to the strength of the received strength of SRS. That is, when the signal strength of the SRS is weak, the channel quality estimation process cannot be satisfactorily performed, so the control unit 12 lowers the priority in such a case. Specifically, when the signal strength of the SRS received from each communication device is greater than or equal to the third threshold value, the SRS can be detected. Therefore, in this case, the control unit 12 sets the priority to 1. Set. On the other hand, when the SRS signal strength of each communication device received in step S1 is less than the third threshold, the SRS cannot be detected, and the control unit 12 sets the priority to 0 in this case. And set.

  The storage unit 13 stores information for calculating priority. FIG. 2 shows information stored in the storage unit 13. The storage unit 13 stores the past SRS detection frequency and the standard deviation of the channel quality based on the past SRS detection for each communication device.

  For example, for “communication device A”, the detection frequency of SRS is “Fa”, and the standard deviation of channel quality is “Da”. Similar information is stored for “communication device B” and “communication device C”. In calculating the priority, statistical data such as past frequency information and standard deviation is used.

  Next, the operation of the radio base station 1 according to the present invention will be described with reference to the flowchart shown in FIG.

  First, the receiving unit 11 of the radio base station 1 receives SRS from one or more communication devices connected to the radio base station 1 (step S1).

  Next, the control part 12 detects the processing load of the process in the wireless base station 1 (step S2). Furthermore, the control part 12 calculates the calculation resource for SRS detection which can be used for SRS detection based on the detected processing load. The calculation resource is calculated by subtracting the total value of the processing loads from the maximum processing amount that can be processed by the radio base station 1.

  Subsequently, the control unit 12 compares the SRS received in step S1 with the calculation resource for SRS detection calculated in step S2, and is sufficient to detect all the SRS received by the calculation resource for SRS detection. (Step S3). That is, the control unit 12 determines whether it is possible to detect all of the SRS received by the calculation resource for SRS detection. In other words, the control unit 12 uses all of the received SRSs based on the calculation resources necessary for performing the SRS detection process and the calculation resources necessary for the data channel decoding process for all of the SRSs received from the one or more communication devices. It is determined whether or not it is possible to perform channel estimation processing.

  If the calculation resource for SRS detection is sufficient as a result of the determination in step S3, the control unit 12 performs the detection process for all the SRSs received in step S1 (step S4). That is, the control unit 12 detects SRSs of all communication devices, performs channel quality estimation processing, and the processing is completed.

  If the calculation resource for SRS detection is not sufficient as a result of the determination in step S3, the control unit 12 reduces the processing amount required for SRS detection without reducing the processing amount required for the data channel decoding process. SRS detection processing is performed only for some communication devices. Specifically, in this case, the control unit 12 calculates the priority of each communication device related to the detection of the SRS received in step S1 (step S5). The priority of each communication device is determined for each communication device based on the past SRS detection frequency, the standard deviation of the channel quality detected by the SRS, or the SRS signal strength. The control unit 12 uses any one of the three criteria as a priority calculation criterion.

  In the case where the control unit 12 uses a standard related to the detection frequency of the SRS, the control unit 12 determines the priority in this case when the detection frequency of the SRS stored in the storage unit 13 is less than the first threshold. Is set to 1. On the other hand, when the SRS detection frequency stored in the storage unit 13 is equal to or higher than the first threshold, the control unit 12 sets the priority to 0.

  When the control unit 12 uses a standard relating to the standard deviation of the channel quality, the control unit 12 determines that the channel quality standard deviation of each communication device stored in the storage unit 13 is greater than or equal to the second threshold. In this case, the priority is set to 1. On the other hand, when the standard deviation of the channel quality of each communication device stored in the storage unit 13 is less than the second threshold, the control unit 12 sets the priority to 0 in this case.

  When the control unit 12 uses the standard related to the signal strength of SRS, the control unit 12 gives priority in this case when the SRS signal strength of each communication device received in step S1 is equal to or greater than the third threshold. Set the degree to 1. On the other hand, when the signal strength of the SRS of each communication device received in step S1 is less than the third threshold, the control unit 12 sets the priority to 0 in this case.

  Subsequently, the control unit 12 performs the detection process only for the SRS related to the communication apparatus whose priority calculated in Step S5 is a predetermined value or more (Step S6), and performs the channel quality estimation process for the communication apparatus. Here, the predetermined value relating to the priority is set to 1, for example. Then, the process ends.

  As described above, according to the radio base station 1 according to the first embodiment, the control unit 12 determines whether or not the calculation resource for SRS detection is sufficient, and when the calculation resource is not sufficient, the priority is a predetermined value. Since only the SRS related to the above communication device is detected, the load on the detection of the SRS can be reduced without increasing the load for detecting the SRS as compared with the decoding load of the data channel, and Real-time channel quality can be estimated. Further, since the load for detecting the SRS is not increased, the base station 1 can be realized by a device having a lower cost.

  In the priority calculation in step S5, the case where the control unit 12 uses only one of the criteria has been described. However, the present invention is not limited to this, and any two or more combinations may be used as the criteria. For example, when all three combinations are used as a reference, the above-described priority is a total value of priority values in each reference. At this time, the priority takes a value from 0 to 3. In this case, the predetermined value is set to 2, for example. Note that this predetermined value is set so that the calculation resource required when detecting an SRS applied to a communication device having a priority equal to or higher than the predetermined value does not exceed the above-described calculation resource for SRS detection.

  In addition, although the case where the reference | standard concerning the standard deviation of channel quality was used was demonstrated in step S5, it is not restricted to this, If it is a statistic value showing the fluctuation value of channel quality, another statistic value can also be made into a reference | standard. For example, a dispersion value of channel quality can be used.

  In step S6, the control unit 12 has been described as detecting only SRS related to a communication device having a priority level equal to or higher than a predetermined value, and not detecting SRS related to a communication device having a priority level lower than the predetermined value. Not limited to this. That is, for a communication device with a priority less than a predetermined value, the control unit 12 detects the SRS by a simple detection algorithm that reduces the number of IDFT points for SRS detection and reduces the calculation processing load. You may do it.

(Embodiment 2)
The second embodiment of the present invention will be described below. FIG. 4 is a block diagram showing a configuration of radio base station 2 according to Embodiment 2 of the present invention. The same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted. The radio base station 2 according to the second embodiment is different from the configuration according to the first embodiment in that the storage unit 13 is not provided. The radio base station 2 according to the second embodiment is different in that the control unit 22 limits the frequency band in which SRS is detected based on the calculation resource for SRS detection.

  Next, the operation of radio base station 2 according to Embodiment 2 will be described with reference to the flowchart shown in FIG. The same operations as those in the first embodiment are denoted by the same reference numerals.

  The first steps S1 to S3 are the same as those in the first embodiment. In step S3, as in the first embodiment, the control unit 22 compares the SRS received in step S1 with the calculation resource for SRS detection calculated in step S2, and the calculation resource for SRS detection is determined. Determine whether it is enough to detect all the received SRS. In step S4, when the calculation resources for SRS detection are sufficient, the control unit 22 detects the SRSs of all communication apparatuses, performs channel quality estimation processing, and ends the processing.

  If the calculation resource for SRS detection is not sufficient as a result of the determination in step S3, the control unit 22 limits the frequency band for detecting SRS based on the calculation resource for SRS detection (step S15). That is, in step S4, the control unit 22 performs SRS detection processing for all the frequency bands received for each communication device. In step S15, the control unit 22 selects the frequency band for performing the detection processing for SRS detection. Only a part of the frequency bandwidth that can be detected by the computational resource is detected, and only a part of the received SRS is detected.

  Then, the control unit 22 performs SRS detection for all communication devices only for a part of the frequency bands restricted in step S15 (step S16), and performs channel quality estimation processing for only the part of the frequency bands. Then, the process ends.

  As described above, according to the radio base station 2 according to the second embodiment, the control unit 22 limits the band for detecting the SRS based on the calculation resource for SRS detection, and detects only the limited SRS. Compared with the decoding load of the data channel, the influence on the decoding process of the more important data channel can be reduced without increasing the load for detecting the SRS, and the real-time channel quality can be estimated.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. For example, the functions included in each member, each means, each step, etc. can be rearranged so as not to be logically contradictory, and a plurality of means, steps, etc. can be combined into one or divided. Is possible.

1, 2 Radio base station 11 Reception unit 12, 22 Control unit 13 Storage unit

Claims (7)

A control unit that performs estimation processing for estimating wireless communication quality with the communication device based on known signals received from one or more communication devices, and decoding processing of a data channel received from the communication device;
The controller is
When the sum of the processing amount required for the estimation process and the processing amount required for the decoding process is greater than or equal to a predetermined threshold for all of the known signals from one or more communication devices, the processing amount required for the decoding process is A radio base station that performs the estimation process only on a part of the known signals from one or more of the communication devices without reducing the frequency.   The control unit receives from one or more communication devices based on a calculation resource necessary for performing the estimation process and a calculation resource necessary for the decoding process for all of the known signals received from the one or more communication devices. The radio base station according to claim 1, wherein it is determined whether or not the estimation process can be performed without reducing a processing amount required for the decoding process for all the received known signals.   The control unit sets a priority for each of the one or more communication devices that transmit the known signal, and performs the estimation process on the known signal transmitted by the communication device having the priority equal to or higher than a predetermined value. The radio base station according to claim 1.   The radio base station according to claim 3, wherein the control unit determines the priority based on a detection frequency of the known signal transmitted by the communication device.   The radio base station according to claim 3, wherein the control unit determines the priority based on a channel quality variation value of the communication device.   The radio base station according to claim 3, wherein the control unit determines the priority based on a signal level of the known signal transmitted by the communication device. A control step for performing estimation processing for estimating wireless communication quality with the communication device based on a known signal received from the communication device, and decoding processing of a data channel received from the communication device,
The control step includes
When the sum of the processing amount required for the estimation process and the processing amount required for the decoding process is greater than or equal to a predetermined threshold for all of the known signals from one or more communication devices, the processing amount required for the decoding process is A wireless communication method, wherein the estimation process is performed only for a part of the known signals from one or more of the communication devices without reduction.

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