JP7014155B2 - Wireless and control devices - Google Patents

Description

The present invention relates to a wireless device, a control device, and a wireless communication system in a wireless communication system configuration in which the functions of a wireless base station are divided into a wireless device and a control device.

As a technique for improving frequency utilization efficiency in a wireless communication system, multi-user MIMO (MU-MIMO: Multi User Multiple Input Multiple Output) transmission that spatially multiplexes signals of a plurality of terminals is being studied.
Non-Patent Document 1 describes a method of determining one precoder for a subband composed of a plurality of subcarriers. After averaging the channel information over multiple subcarriers in the subband and calculating the averaging channel information of the subband, the precoder is calculated from the averaging channel information. Also, when deciding the terminal combination for MU-MIMO, the transmission characteristics when MU-MIMO transmission is performed using the channel information averaged in the subband and the precoder generated from the channel information are determined. After estimating, the combination of terminals that maximizes the predetermined terminal selection index is selected.

Non-Patent Document 2 describes the frequency characteristics, and the range in which the frequency characteristics can be regarded as constant is called a coherent bandwidth. It also describes the relationship between coherent bandwidth and delay spread.

On the other hand, small cells with low transmission power and a narrow cell coverage range are being introduced in order to expand the network capacity of wireless communication systems. In Non-Patent Document 3, a C-RAN (Cloud RAN) configuration for efficiently operating a small cell is studied. In C-RAN, the baseband processing function of the small cell is divided into the wireless device on the antenna side and the control device on the core network side, and the control device integrates a part of the baseband processing function of multiple small cells. Be done. Non-Patent Document 3 describes a plurality of types of C-RAN configurations depending on the method of dividing the baseband processing function, and is required for the transmission line (front hole) between the wireless device and the control device depending on each configuration. The transmission capacity and the ease of coordinated control between cells are described.

Japanese Unexamined Patent Publication No. 2012-114700 Special Table 2005-514801 Gazette

X. Wang, C. Na, X. Hou, H. Jiang, H. Kayama, “Wideband and high-order multi-user spatial multiplexing transmission with massive MIMO for future radio access”, IEEE PIMRC 2015, Aug. 2015. Minoru Okada, “Basics of OFDM,” Microwave Workshops and Exhibition, 2003. [Search on April 27, 2016] <http://www.apmc-mwe.org/mwe2004/ja_mwe2003_TL/TL02-02.pdf> Small Cell Forum, "Small cell virtualization functional spirits and use cases", ver. 159.05.1.01, June 2015.

However, as described above, in the prior art, when determining the spatial multiplex terminal before transmitting the data, the channel fluctuation within the range in which the channel information is averaged is not taken into consideration, and the averaged channel information is used. On the other hand, the spatial multiplex terminal is decided. Therefore, when actually transmitting data, interference between terminals occurs due to channel fluctuation within the channel information averaging range that could not be considered due to the influence of averaging, and the throughput deteriorates. Therefore, it is necessary to determine the spatial multiplex terminal in consideration of the channel fluctuation within the channel information averaging range.

In the first aspect, the wireless device is a channel variation processing unit that generates information for spatial multiplex terminal selection using channel estimates between the wireless terminal and the wireless device, and the spatial multiplex terminal selection information. A wireless device including a transmission unit that transmits the information to the control device and a reception unit that receives scheduling information generated by using the spatial multiplex terminal selection information.

In the second aspect, the wireless device is a channel variation information generation unit that generates channel variation information using the channel estimation value between the wireless terminal and the wireless device, and the channel variation information is transmitted to the control device. A transmission unit for transmitting and a receiving unit for receiving scheduling information generated by using spatial multiplex terminal selection information are provided, and the spatial multiplex terminal selection information is information calculated using the variation information. , A wireless device characterized by that.

In the third aspect, the control device uses the receiving unit for receiving the spatial multiplex terminal selection information using the channel estimated value between the wireless terminal and the wireless device, and the spatial multiplex terminal selection information. A control device including a scheduling unit that generates scheduling information of a terminal and a transmission unit that transmits the scheduling information to the wireless device.

In the fourth aspect, the control device is a receiving unit that receives channel variation information using the channel estimation value between the wireless terminal and the wireless device, and is used for spatial multiplex terminal selection using the channel variation information. A spatial multiplex terminal selection information generation unit that generates information, a scheduling unit that generates terminal scheduling information using the spatial multiplex terminal selection information, and a transmission unit that transmits the scheduling information to the wireless device. Control device to be equipped.

According to an exemplary embodiment, the spatial multiplex terminal is appropriately determined according to the variation of the propagation path. Interference between terminals can be suppressed and throughput is improved.

The configuration of the communication device according to the first embodiment is shown. The sequence diagram of the communication apparatus which concerns on 1st Embodiment is shown. The configuration of the communication device according to the second embodiment is shown. The sequence diagram of the communication apparatus which concerns on the 2nd Embodiment is shown. The flowchart of the scheduling part which concerns on the 2nd Embodiment is shown. The spatial multiplex terminal selection metric according to the second embodiment is shown. The spatial multiplex terminal selection metric according to the third embodiment is shown. The flowchart of the scheduling part which concerns on 3rd Embodiment is shown. The spatial multiplex terminal selection metric according to the 4th Embodiment is shown. The flowchart of the scheduling part which concerns on 4th Embodiment is shown. The configuration of the wireless communication system according to the fifth embodiment is shown. The configuration of the communication device according to one aspect of the fifth embodiment is shown. The sequence diagram of the communication apparatus which concerns on one aspect of 5th Embodiment is shown. The configuration of the communication device according to one aspect of the fifth embodiment is shown. The sequence diagram of the communication apparatus which concerns on one aspect of 5th Embodiment is shown.

In Non-Patent Document 1, channel information is averaged on the frequency axis, but the same processing can be performed on the time axis. In this way, it is possible to improve the channel estimation accuracy by averaging the channel information over a plurality of radio resources in terms of both time and frequency. Here, the range for averaging channel information is called the channel information averaging range.

Conventionally, in MIMO transmission, channel information has been averaged within the channel information averaging range. However, when the channel within the channel information averaging range fluctuates drastically, interference between terminals that was not expected when selecting the terminal occurs during actual transmission, and even if the spatial multiplex is increased, the terminal is more effective than the improvement effect of the spatial multiplex. There is a problem that the influence of interfering becomes large and the actual transmission characteristics deteriorate.

In one aspect of the present invention, in the MU-MIMO transmission device, the channel estimation unit that performs channel estimation and the channel variation within the channel information averaging range are taken into consideration, and information for spatial multiplex terminal selection is generated and scheduled. It includes a channel variation processing unit that transmits to the unit and a scheduling unit that performs scheduling using the received spatial multiplex terminal selection information. When performing MU-MIMO transmission, scheduling is performed using spatial multiplex terminal selection information that takes into account channel fluctuations within the channel information averaging range, so interference between terminals can be suppressed and throughput can be improved.

Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. In each drawing, the same or corresponding elements are designated by the same reference numerals, and duplicate explanations are omitted as necessary for the sake of clarity of explanation. Those skilled in the art can apply the principles and ideas grasped from the embodiments specifically described below to various types of wireless systems.

The plurality of embodiments described below may be implemented independently or in combination as appropriate. These plurality of embodiments have novel features that differ from each other. Therefore, these plurality of embodiments contribute to solving different purposes or problems, and contribute to different effects.

<First embodiment>
[Structure of the first embodiment]
A block diagram showing the configuration of the apparatus 1000 in the first embodiment is shown in FIG. The device 1000 includes an antenna unit 1100, a channel estimation unit 1200, a channel variation processing unit 1300, and a scheduling unit 1400.

[Operation of the first embodiment]
The operation of the apparatus 1000 will be described with reference to the sequence diagram of FIG. The antenna unit 1100 receives a reference signal received from the terminal and outputs it to the channel estimation unit 1200 (S201).

The channel estimation unit 1200 receives the reception result of the reference signal from the antenna unit 1100, calculates the channel estimation value (propagation path information) between the terminal and the device 1000 (S202), and outputs it to the channel variation processing unit 1300. (S203).

The channel variation processing unit 1300 calculates spatial multiplex terminal selection information that suppresses selection of terminals with large channel variation and promotes terminal selection with small variation based on the channel estimation value input from the channel estimation unit 1200. (S204), output to the scheduling unit 1400 (S205).

The scheduling unit 1400 selects a terminal for spatial multiplexing based on the spatial multiplex terminal selection information input from the channel variation processing unit 1300 and the channel estimated value input from the channel estimation unit 1200 in S206 (S207). ..

The information for spatial multiplex terminal selection may be spatial multiplex terminal selection metric, for example, terminal suppression information for suppressing terminal selection, or terminal selection promotion information indicating a terminal with little fluctuation. Further, it may be the maximum value of the number of spatial multiplex terminals, the correlation value threshold value, or the terminal selection index correction value.

[Effect of the first embodiment]
According to the first embodiment, since the terminal to be spatially multiplexed is selected using the spatial multiplex terminal selection information in consideration of the channel variation, scheduling corresponding to the channel variation within the channel information averaging range can be performed. .. As a result, interference between terminals can be suppressed and throughput can be improved.

<Second embodiment>
Conventionally, in MIMO transmission, channel information has been averaged within the channel information averaging range. However, when the channel within the channel information averaging range fluctuates drastically, interference between terminals that was not expected when selecting the terminal occurs during actual transmission, and even if the spatial multiplex is increased, the terminal is more effective than the improvement effect of the spatial multiplex. The influence of inter-interference became large, and the actual transmission characteristics could deteriorate.

According to the second embodiment, terminals to be spatially multiplexed are selected in consideration of channel variation information within the channel information averaging range, spatial multiplexing terminals are appropriately determined according to channel variation, and terminals are appropriately determined. Suppresses interference and improves throughput.

[Structure in the second embodiment]
A block diagram showing the configuration of the apparatus 3000 in the second embodiment is shown in FIG. The device 3000 includes an antenna unit 3100, a channel estimation unit 3200, a channel variation processing unit 3300, and a scheduling unit 3400. Further, the channel variation processing unit 3300 includes a channel variation information calculation unit 3310 and a spatial multiplex terminal selection metric calculation unit 3320.

[Operation in the second embodiment]
The operation of the apparatus 3000 will be described with reference to the sequence diagram of FIG.

The antenna unit 3100 receives a reference signal received from the terminal and outputs it to the channel estimation unit 3200 (S401).

The channel estimation unit 3200 receives the reception result of the reference signal from the antenna unit 3100, calculates the channel estimation value between the terminal and the device 3000 (S402), and sends it to the channel variation information calculation unit 3310 of the channel variation processing unit 3300. Output (S403).

The channel variation information calculation unit 3310 calculates the channel variation information for suppressing the selection of the terminal having a large channel variation based on the channel estimation value input from the channel estimation unit 3200 (S404), and the spatial multiplex terminal selection metric. It is output to the calculation unit 3320 (S405).

The spatial multiplex terminal selection metric calculation unit 3320 calculates the spatial multiplex terminal selection metric based on the channel variation information input from the channel variation information calculation unit 3310 (S406), and outputs the spatial multiplex terminal selection metric to the scheduling unit 3400 (S407).

The scheduling unit 3400 selects terminals to be spatially multiplexed based on the spatial multiplex terminal selection metric input from the spatial multiplex terminal selection metric calculation unit 3320 and the channel estimation value input from the channel estimation unit 3200 in S408. S409).

The channel estimation value calculated in the operation S402 is the average value of the channel estimation information estimated at different frequencies. The channel estimate is calculated for a relatively narrow frequency domain such as subcarriers and resource blocks, but in the constant frequency domain from the viewpoint of improving channel estimation accuracy, scheduling the entire system band, and reducing precoder calculation. Handles averaged channel information. The channel estimates of the subcarriers and resource blocks may be used for averaging the channel information, or the transmission covariance matrix calculated from the channel estimates may be used. Further, the averaging of this channel information may be performed on the time axis.

The details of the operation S404 will be described. The channel variation information calculation unit 3310 generates channel variation information using the channel estimation value input from the channel estimation unit 3200.

The channel fluctuation information is information indicating the magnitude of the channel fluctuation within the channel information averaging range. For example, as information representing the magnitude of channel variation on the frequency axis, it is a delay spread value calculated from a profile in the time domain of an estimated value of the channel response. The channel variation information may be a coherent bandwidth calculated from the reciprocal of the delay spread. Further, the channel fluctuation information may be channel fluctuation information on the time axis, specifically, the phase fluctuation amount per constant frequency of the estimated value of the channel response, or measured using GPS (Global Positioning System). It may be the moving speed of the terminal.

Further, which of the time axis fluctuation and the frequency axis fluctuation is used for the channel fluctuation information may be determined by the averaging process applied to the stored channel estimation value. When the channel information is averaged on the time axis and the frequency axis, the fluctuation information on the time axis and the frequency axis is used as the channel fluctuation information, respectively.

The details of the operation S406 will be described. The spatial multiplex terminal selection metric calculation unit 3320 calculates the spatial multiplex terminal selection metric based on the channel variation information input from the channel variation information calculation unit 3310.

As the spatial multiplex terminal selection metric in the second embodiment, as shown in FIG. 6, a table showing the correspondence between the terminal index and, for example, the maximum value of the number of spatial multiplex terminals is created. The maximum value of the number of spatial multiplex terminals may be set smaller for terminals with larger channel fluctuations, and may be set larger for terminals with smaller channel fluctuations.

As a method of determining the maximum number of spatial multiplex terminals from the channel variation information for each terminal, a method of calculating the channel variation information and the optimum number of spatial multiplex terminals by a computer simulation in advance, or an initial value of the maximum number of multiplex terminals. Is set as the maximum value in the system, and there is a method of reducing the maximum number of spatial multiplex terminals according to at least one of the number of NACKs (Negative ACKnowled genes) fed back from the terminals and the channel fluctuation information. Further, the spatial multiplex terminal selection metric does not necessarily have to be performed for all terminals having channel fluctuation information, and a predetermined threshold value is set for the channel fluctuation information, and the terminal whose channel fluctuation is larger than the predetermined threshold value. Only spatial multiplex terminal selection metrics may be calculated.

The details of the operation S409 will be described. The scheduling unit 3400 determines a combination of terminals that perform spatial multiplex transmission based on the channel estimated value input from the channel estimation unit 3200 and the spatial multiplex terminal selection metric input from the spatial multiplex terminal selection metric calculation unit 3320. do.

By the way, there is a full search algorithm as the most basic spatial multiplex terminal selection method. In the full search algorithm, the combination that maximizes the terminal selection metric is selected from all the combinations of the terminals and the number of transmission layers of each terminal. In this embodiment, an example of improving the full search algorithm by using the spatial multiplex terminal selection information is shown.

The operation flow of the scheduling unit 3400 in the second embodiment is shown in FIG.

The scheduling set U is defined as a set indicating the terminals to be spatially multiplexed and the number of layers to be spatially multiplexed for each terminal. Each element of U is a combination of the terminal index and the index of the layer in the terminal. Further, the scheduling set group Ω is defined as a set whose elements are the candidates of the scheduling set selected by the scheduling unit 3400. The scheduling set group Ω is expressed by the following equation (1).

Here, U _k is the kth scheduling set in the scheduling set group Ω and is expressed by the following equation (2).

Here, L _k is the total number of multiple layers in the scheduling set of the kth element in the scheduling set group Ω, and u (k, l) is the lth element in the scheduling set U _k , and the terminal index and each terminal. Represents a set with a layer index. For example, when the lth element of the scheduling set Uk indicates the _{ilayerth layer} of the _iuserth terminal, u ( _k , l) is expressed by the following equation (3).

First, a combination of all multiplex terminals and the number of multiplex layers is generated in consideration of the total number of multiplex layers in the system and the maximum number of multiplex layers of each terminal (S501), and the scheduling set group Ω is used.

Select the scheduling set _Uk from the scheduling set group Ω. For each scheduling set _Uk , the maximum number of spatial multiplex terminals (maximum number of multiplex layers) is calculated based on the spatial multiplex terminal selection metric input from the spatial multiplex terminal selection metric calculation unit 3320 (S502). Specifically, using the channel fluctuation information table, the maximum number of multiple layers N _layer ( _Uk ) corresponding to the scheduling set _Uk is calculated by the following equation (4).

Here, Table (u (k, l)) represents the maximum number of multiplex layers obtained by referring to the terminal index specified by u (k, l) in the table of spatial multiplex terminal selection metrics.

When the N _layer (U _k ) is larger than the total number of multiplex layers L _k of the scheduling set U _k , the scheduling set U _k is stored in the scheduling set group Ω'. Based on the channel estimation value input from the channel estimation unit 3200, the terminal selection index M ( _Uk ) is calculated for all the scheduling set _Uk of the scheduling set group Ω'(S503). As a specific terminal selection index, a Max C / I norm or a PF (Proportional Fairness) norm can be used.

In the case of the _MaxC / I norm, the received SINR (Signal to Interference plus Noise Power Ratio) of the terminal and layer included in the scheduling set UK is estimated, and the estimated SINR is converted into an instantaneous rate by the theoretical formula of Shannon capacity. , Let the sum of the instantaneous rates be the terminal selection index M ( _Uk ).

In the case of the PF norm, radio resources are allocated at the ratio of the instantaneous throughput to the average throughput of the target mobile station. In the case of the PF norm, the sum of the instantaneous rates divided by the average rate is used as the terminal selection index M ( _Uk ), not the sum of the instantaneous rates.

After that, the scheduling set _Uk at which the terminal selection index M ( _Uk ) is maximized is set as the spatial multiplex terminal selection result UP ( _S504 ). The calculation formula is expressed by the following formula (5).

In the operation of the scheduling unit 3400, the terminal selection index related to the MU-MIMO transmission characteristic is calculated based on the channel information, and the terminal combination that maximizes this is selected.

[Effect in the second embodiment]
Conventionally, in MIMO transmission, channel information has been averaged within the channel information averaging range. However, when the channel within the channel information averaging range fluctuates drastically, interference between terminals that was not expected when selecting the terminal occurs during actual transmission, and even if the spatial multiplex is increased, the terminal is more effective than the improvement effect of the spatial multiplex. The influence of inter-interference became large, and the actual transmission characteristics could deteriorate.

According to the second embodiment, since the terminal to be spatially multiplexed is selected in consideration of the channel variation information within the channel information averaging range, the spatial multiplexing terminal appropriately determines according to the channel variation. Can be done. As a result, interference between terminals is suppressed and throughput is improved.

<Third embodiment>
In general, the spatial separation performance between terminals with high correlation is greatly affected by the precoder error. While the assumed channel is a channel averaged within the subband, in the actual channel, if the channel fluctuation is large within the subband, the spatial separation by the precoder may not work.

According to the third embodiment, for users with large channel fluctuations, for example, users with a large difference between the assumed channel and the actual channel, the spatially multiplexed terminals are limited to those with low correlation, the interference between terminals is reduced, and the throughput is reduced. To improve.

[Structure / operation in the third embodiment]
The configuration and operation of the apparatus 3000 in the third embodiment are the same as those in the block diagram 3 and the sequence diagram 4 described in the second embodiment, except for the operations S406 and S409 described below.

The operation S406 will be described. The spatial multiplex terminal selection metric calculation unit 3320 calculates the spatial multiplex terminal selection metric based on the channel variation information input from the channel variation information calculation unit 3310.

The spatial multiplex terminal selection metric in the third embodiment is a table showing the threshold value of the correlation value for the combination of the two terminal indexes as shown in FIG. 7. In the spatial multiplex terminal selection metric, the threshold value of the correlation value is set lower for terminals with larger channel fluctuations. As a specific method of setting the threshold, a method of calculating the channel fluctuation information and the optimum number of spatial multiplex terminals by performing a computer simulation in advance, or setting the initial value of the maximum number of multiplex terminals as the maximum value in the system and using the terminal. There is a method of reducing the maximum number of spatial multiplex terminals according to at least one of the number of NACKs fed back and the channel fluctuation information.

Also, it is not necessary to calculate the spatial multiplex terminal selection metric for all terminals for which channel variation information has been input. For example, a method of using a predetermined threshold value for channel fluctuation information, determining a terminal having a large channel fluctuation, and calculating a spatial multiplex terminal selection metric only for a terminal combination including a terminal having a large channel fluctuation, or a method having a large channel fluctuation. There is a way to calculate the spatial multiplex terminal selection metric for a combination of terminals only.

The operation S409 will be described. The scheduling unit 3400 determines a combination of terminals that perform spatial multiplex transmission based on the channel estimated value input from the channel estimation unit 3200 and the spatial multiplex terminal selection metric input from the spatial multiplex terminal selection metric calculation unit 3320. do.

In this embodiment, as in the second embodiment, an example of improving the full search algorithm by using the spatial multiplex terminal selection metric determined based on the magnitude of the channel variation is shown.

The operation flow of the scheduling unit 3400 in the third embodiment is shown in FIG.

First, the scheduling set group Ω of all patterns is generated as in S501 in the second embodiment (S801).

Select any scheduling set _Uk from the scheduling set group Ω. _Arbitrary two elements are selected from the selected scheduling set UK, and the correlation value between the two terminals corresponding to the two elements is calculated (S802). For example, when the i-th terminal and the i'th terminal are selected, the correlation value of the two terminals is calculated by the following equation (6).

Here, h'i and _h'i'are the channel vectors of the _i -th and i'th terminals, respectively, and may be eigenvectors corresponding to the index of the layer of each terminal. For example, in the case of the lth layer of the kth terminal, it is the lth eigenvector of the channel of the kth terminal.
However, it is assumed that the eigenvectors are sorted in descending order of the corresponding eigenvalues.

Further, as shown in the following equation (7), the channel vector may be a row vector having the largest norm in the channel matrix.

Here, Row (A) is the number of rows in the matrix A. Further, h _{i and j} are row vectors on the jth row in the channel matrix of the i-th terminal, and are defined by the following equations (8) and (9).

Here, Hi is the channel matrix at the _i -th terminal _{, hi and j} are the channel vectors related to the j-th receiving antenna at the i-th terminal _{, and hi, j and k} are the j-th receiving antennas at the i-th terminal. And the channel response between the kth antenna.

Further, in the table of spatial multiplex terminal selection metrics, the threshold value of the correlation value is calculated based on the two selected terminal indexes (S803).

The calculated correlation value is compared with the correlation value threshold value, and the scheduling set _Uk that does not include an element whose correlation value between terminals is larger than the threshold value of the correlation value is stored in the selectable scheduling set group Ω'(. S804).

The scheduling set that maximizes the terminal selection index is selected from all the elements of the selectable scheduling set group Ω'(S805).

[Effect in the third embodiment]
In general, the spatial separation performance between terminals with high correlation is greatly affected by the precoder error. While the assumed channel is a channel averaged within the subband, in the actual channel, if the channel fluctuation is large within the subband, the spatial separation by the precoder may not work.

In the third embodiment, for users with large channel fluctuations, for example, users with a large difference between the assumed channel and the actual channel, the spatially multiplexed terminals are limited to those with low correlation to reduce the interference between terminals. Throughput can be improved.

<Fourth Embodiment>
In the first to third embodiments, the limitation of the user or the combination of users to be scheduled based on the channel fluctuation information and the scheduling are performed independently. The behavior of user combinations may not be optimal from the viewpoint of throughput characteristics and fairness among users, which are considered in the conventional scheduler. For example, by excluding users who have a lot of fluctuations in terminals but good average reception quality from the selection candidates, the throughput improvement effect may be limited, and users who have a lot of fluctuations are excluded from scheduling candidates. There was a possibility that the fairness would deteriorate.

According to the fourth embodiment, by correcting the scheduling metric based on the channel variation information, the channel variation within the channel information averaging range and the factors considered by the conventional scheduler are simultaneously considered. It improves the factors considered in the scheduler's metrics, such as estimated throughput characteristics and fairness among users.

[Structure / operation in the fourth embodiment]
The configuration and operation of the apparatus 3000 are the same as those of the block diagram 3 and the sequence diagram 4 described in the second and third embodiments, except for the operations S406 and S409 described below.

The operation S406 will be described. As shown in FIG. 9, the spatial multiplex terminal selection metric is a table of a terminal index and a terminal selection index correction value for correcting the terminal selection index. Further, in the spatial multiplex terminal selection metric, the terminal selection index correction value is set smaller as the channel fluctuation in the subband is larger. As a specific method of setting the terminal selection index correction value, a method of performing a computer simulation in advance to calculate the channel fluctuation information and the optimum number of spatial multiplex terminals, or for example, 0 is set as the initial value and feedback is given from the terminal. There is a method of adding a correction value according to at least one of the number of NACKs and the channel fluctuation information.

The details of the operation S409 will be described. The scheduling unit 3400 determines a combination of terminals that perform spatial multiplex transmission based on the channel estimated value input from the channel estimation unit 3200 and the spatial multiplex terminal selection metric input from the spatial multiplex terminal selection metric calculation unit 3320. do.

The operation of the scheduling unit 3400 in the fourth embodiment will be described with reference to the operation flow of FIG.

First, the scheduling set group Ω of all patterns is generated as in S501 in the second embodiment (S1001).

Next, an arbitrary scheduling set _Uk is selected from the scheduling set group Ω. A predetermined terminal selection index is calculated for the selected scheduling set UK ( _S1002 ).

Further, the terminal selection index of each scheduling set U is corrected based on the spatial multiplex terminal selection metric input from the spatial multiplex terminal selection metric calculation unit 3320 (S1003). The correction value of the terminal selection index for the scheduling set may be the total value of the correction values of the terminal selection index determined by referring to the table of spatial multiplex terminal selection metrics from the index of each terminal constituting the scheduling set U _k . It may be the maximum value among the correction values of the terminal. For example, when the total value of the correction values of each terminal is used, the correction value ΔM ( _Uk ) is calculated by the following equation (10).

ΔM (i _user ) is a terminal selection index correction value obtained by referring to the terminal index _user from a table of spatial multiplex terminal selection metrics.

The corrected terminal selection index is calculated by the following equation (11).

The scheduling set that maximizes the terminal selection index is selected from the scheduling set group Ω (S1004).

[Effect in the fourth embodiment]
In the first to third embodiments, the limitation of the user or the combination of users to be scheduled based on the channel fluctuation information and the scheduling are performed independently. The behavior of user combinations may not be optimal from the viewpoint of throughput characteristics and fairness among users, which are considered in the conventional scheduler. For example, by excluding users who have a lot of fluctuations in terminals but good average reception quality from the selection candidates, the throughput improvement effect may be limited, and users who have a lot of fluctuations are excluded from scheduling candidates. There was a possibility that the fairness would deteriorate.

According to the fourth embodiment, by correcting the scheduling metric based on the channel fluctuation information, the channel fluctuation within the channel information averaging range and the factors considered by the conventional scheduler are taken into consideration at the same time. Factors considered in the metric, such as estimated throughput characteristics and fairness among users, are improved.

<Fifth Embodiment>
[Structure in the fifth embodiment]
The MIMO wireless communication system according to the present invention may have a configuration as shown in the block diagram shown in FIG. The wireless communication system includes a core network 1, a control device 11100, a wireless device 1120-1 (wireless device # 1), a wireless device 11200-2 (wireless device # 2), a wireless terminal 2-1 (wireless terminal # 1), and wireless. It is provided with terminal 2-2 (wireless terminal # 2) and wireless terminal 2-3 (wireless terminal # 3). When it is not necessary to distinguish between the wireless devices 1120-1 and 11200-2, it is simply referred to as the wireless device 11200. Similarly, when the distinction is unnecessary for the wireless terminals 2-1, 2-2, and 2-3, they are referred to as wireless terminals 2. Further, the wireless communication system shown in FIG. 11 includes two wireless devices 11200, but the number of wireless devices 11200 is not limited to this. For example, there may be two or more, or one. Similarly, the number of wireless terminals 2 is not limited. Further, although a wireless terminal is used as an example here, a wireless device having a relay capability may be used.

The control device 11100 and the wireless device 11200 are provided at physically separated positions and are connected via a transmission line 30. The transmission line 30 is a medium used for information transmission such as an optical fiber, a metal cable, and a wireless channel. The wireless device 11200 and the wireless terminal 2 are connected via a wireless propagation path. The control device 11100 includes a center radio signal processing unit 11110 and a transmission line interface 11120 (transmission line IF). The transmission line IF 11120 performs processing corresponding to the standard of the transmission line 30 in order to communicate with the wireless device 11200 via the transmission line 30.

The radio device 11200 includes a transmission line interface 11210 (transmission line IF), a remote radio signal processing unit 11220, and an antenna unit 11230 having a plurality of antennas.

The wireless terminal 2 includes an antenna and a wireless transmission / reception unit.

[Operation in the fifth embodiment]
As a first aspect according to the fifth embodiment, the channel estimation unit 1200 and the antenna unit 1100 shown in FIG. 1 are in the radio device 11200 shown in FIG. 11, and the channel variation processing unit shown in FIG. There is an embodiment in which the 1300 and the scheduling unit 1400 are included in the center radio signal processing unit 11110 shown in FIG. The operation is the same as the sequence shown in FIG. 2 described in the first embodiment. In S203 of this embodiment, the radio device 11200 transmits the channel estimated value to the center radio signal processing unit through the transmission line IF.

According to the first aspect, since the control device is provided with the channel variation processing unit, it is not necessary to provide the wireless device with a function for considering the channel variation, and the cost of the wireless device can be reduced.

As the second aspect according to the fifth embodiment, there is the configuration shown in FIG. FIG. 12 is a block diagram showing a configuration of a wireless communication system. The center radio signal processing unit 11110 of the control device 11100 has a scheduling unit 3400 and a spatial multiplex terminal selection metric calculation unit 3320. The remote radio signal processing unit 11220 of the radio device 11200 includes a channel variation information calculation unit 3310, a channel estimation unit 3200, and an antenna unit 3100.

FIG. 13 is the same as the sequence of FIG. 4 shown in the second to fourth embodiments except for the operations S405 and S408. The operation S405 transmits channel variation information from the remote radio signal processing unit 11220 of the radio device 11200 to the center radio signal processing unit 11110 of the control device 11100 through the transmission line IF30. The operation S408 transmits a channel estimated value from the remote radio signal processing unit 11220 of the radio device 11200 to the center radio signal processing unit 11110 of the control device 11100 through the transmission line IF30.

According to the second aspect, since the wireless device is provided with the channel fluctuation information calculation unit, it is not necessary to provide the control device with a function for considering the channel fluctuation, and the cost of the control device can be reduced.

As a third aspect according to the fifth embodiment, there is a configuration shown in FIG. FIG. 14 is a block diagram showing a configuration of a wireless communication system. The center radio signal processing unit 11110 of the control device 11100 has a scheduling unit 3400. The remote radio signal processing unit 11220 of the radio device 11200 includes a spatial multiplex terminal selection metric calculation unit 3320, a channel variation information calculation unit 3310, a channel estimation unit 3200, and an antenna unit 3100.

FIG. 15 is the same as the sequence of FIG. 4 shown in the second to fourth embodiments except for the operations S407 and S408. The operation S407 transmits a spatial multiplex terminal selection metric from the remote radio signal processing unit 11220 of the radio device 11200 to the center radio signal processing unit 11110 of the control device 11100 through the transmission line IF30. The spatial multiplex terminal selection metric may be the spatial multiplex terminal selection metric described in the second to fourth embodiments. The operation S408 transmits a channel estimated value from the remote radio signal processing unit 11220 of the radio device 11200 to the center radio signal processing unit 11110 of the control device 11100 through the transmission line IF30.

According to the third aspect, since the wireless device is provided with the channel variation processing unit, it is not necessary to provide the control device with a function for considering the channel variation, and the cost of the control device can be reduced.

[Effect in the fifth embodiment]
By adopting the C-RAN configuration according to the fifth embodiment, it is possible to reduce the cost required for expanding the cell coverage.

<Other embodiments>
The above exemplary embodiments will be described herein with respect to wireless terminals. The communication terminal may also be referred to as a wireless terminal, a mobile terminal or a user terminal. In addition, the terminal is a function of a system, a subscriber unit, a subscriber station, a mobile station, a wireless terminal, a mobile device, a node, a device, a remote station, a remote terminal, a wireless communication device, a wireless communication device, a wireless communication device or a user agent. May include some or all of the sex. Terminals include cellular phones, cordless phones, session initiation protocol (SIP) phones, smartphones, wireless local loop (WLL) stations, personal digital assistants (PDAs), laptops, and tablets. , Netbooks, smart books, handheld communication devices, handheld computing devices, satellite radios, wireless modem cards and / or other processing devices that communicate via wireless systems.

Further, it can be realized by the above-mentioned wireless communication terminal, wireless communication system, hardware, software, or a combination thereof. Further, the wireless communication method of the wireless communication system described above can also be realized by hardware, software, or a combination thereof. Here, what is realized by software means that it is realized by a computer reading and executing a program.
Programs can be stored and supplied to a computer using various types of non-transitory computer readable medium. Non-temporary computer-readable media include various types of tangible storage media. Examples of non-temporary computer-readable media include magnetic recording media (eg, flexible discs, magnetic tapes, hard disk drives), opto-magnetic recording media (eg, opto-magnetic discs), CD-ROMs (Compact Disc Read Only Memory), and the like. CD-R (Compact Disk Record), CD-R / W (Compact Disk Rewritable), DVD-ROM (Digital Versaille Disc ROM), DVD-R (Digital VersailLe DesiR Desircycle) ), Semiconductor memory (for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (Random Access Memory)). The program may also be supplied to the computer by various types of temporary computer-readable media. Examples of temporary computer readable media include electrical, optical, and electromagnetic waves. The temporary computer-readable medium can supply the program to the computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path.

Furthermore, the above-described embodiment is merely an example relating to the application of the technical idea obtained by the inventor of the present invention. That is, the technical idea is not limited to the above-described embodiment, and it goes without saying that various changes can be made. For example, some or all of the above embodiments may be described as, but not limited to, the following appendixes.

Some or all of the above embodiments may also be described, but not limited to:
(Additional idea)
(Appendix 1)
A channel variation processing unit that is a wireless device and generates spatial multiplex terminal selection information using a channel estimated value between the wireless terminal and the wireless device, and transmits the spatial multiplex terminal selection information to the control device. A wireless device including a transmitting unit for receiving the scheduling information generated by using the spatial multiplex terminal selection information from the control device.

(Appendix 2)
In the wireless device according to Appendix 1, the channel variation processing unit includes a channel variation information generation unit and an information generation unit for spatial multiplex terminal selection, and the channel variation information generation unit is the channel estimation value. The base station is characterized in that channel variation information is generated using the channel variation information, and the spatial multiplex terminal selection information generation unit generates spatial multiplex terminal selection information using the channel variation information.

(Appendix 3)
A wireless device, a channel variation information generation unit that generates channel variation information using a channel estimation value between a wireless terminal and the wireless device, a transmission unit that transmits the channel variation information to a control device, and a space. The spatial multiplex terminal selection information includes a receiving unit that receives scheduling information generated using the multiplex terminal selection information from the control device, and the spatial multiplex terminal selection information is information calculated using the channel fluctuation information. A wireless device characterized by that.

(Appendix 4)
The wireless device according to any one of Supplementary note 1 to 3, wherein the spatial multiplex terminal selection information includes a spatial multiplex terminal selection metric, a spatial multiplex terminal suppression information, a maximum number of spatial multiplex terminals, and a terminal correlation value threshold value. , A wireless device characterized in that it is one of the terminal selection index correction values.

(Appendix 5)
The radio device according to any one of Supplementary note 1 to 4, wherein the channel fluctuation information is channel fluctuation within the channel information averaging range on the frequency axis or the time axis.

(Appendix 6)
The wireless device according to any one of Supplementary note 1 to 5, wherein the scheduling information is scheduling information for spatially multiplexing allocated resources to a plurality of terminals.

(Appendix 7)
The wireless device according to any one of Supplementary note 1 to 6, wherein the wireless device is physically separated from the control device and connected via a transmission line.

(Appendix 8)
The wireless device according to any one of Supplementary note 1 to 7, wherein the wireless terminal is a wireless terminal that communicates with the wireless device or a wireless terminal that communicates with another wireless device.

(Appendix 9)
A control device, a receiving unit that receives information for spatial multiplex terminal selection using channel estimates between wireless terminals and wireless devices from the wireless device, and a terminal using the spatial multiplex terminal selection information. A control device including a scheduling unit that generates scheduling information and a transmission unit that transmits the scheduling information to the wireless device.

(Appendix 10)
A control device for selecting a spatial multiplex terminal using the channel variation information and a receiving unit that receives the channel variation information generated by using the channel estimation value between the wireless terminal and the wireless device from the wireless device. A spatial multiplex terminal selection information generation unit that generates information, a scheduling unit that generates terminal scheduling information using the spatial multiplex terminal selection information, and a transmission unit that transmits the scheduling information to the wireless device. Control device to be equipped.

(Appendix 11)
The control device according to Appendix 9 or 10, wherein the spatial multiplex terminal selection information includes a spatial multiplex terminal selection metric, spatial multiplex terminal suppression information, a maximum number of spatial multiplex terminals, a terminal correlation value threshold value, and a terminal selection index. A control device characterized in that it is one of the correction values.

(Appendix 12)
The control device according to Appendix 10, wherein the channel fluctuation information is channel fluctuation within the channel information averaging range of the frequency axis or the time axis.

(Appendix 13)
The control device according to any one of Supplementary note 9 to 12, wherein the scheduling information is scheduling information for spatially multiplexing allocated resources to a plurality of terminals.

(Appendix 14)
The control device according to any one of Supplementary note 9 to 13, wherein the control device is physically separated from the radio device and connected via a transmission line.

(Appendix 15)
The control device according to any one of Supplementary note 9 to 14, wherein the wireless terminal is a wireless terminal that communicates with the wireless device or a wireless terminal that communicates with another wireless device.

Although the invention of the present application has been described above with reference to the embodiments, the invention of the present application is not limited to the above-described embodiment. Various changes that can be understood by those skilled in the art can be made within the scope of the present invention in terms of the configuration and details of the present invention.

This application claims priority on the basis of Japanese application Japanese Patent Application No. 2016-094657 filed on May 10, 2016 and incorporates all of its disclosures herein.

1 Core network 2,2-1,2-2,2-3 Wireless terminal 30 Transmission line 1000 Device 1100 Antenna section 1200 Channel estimation section 1300 Channel variation processing section 1400 Scheduling section 3000 Device 3100 Antenna section 3200 Channel estimation section 3300 Channel variation Processing unit 3310 Channel fluctuation information calculation unit 3320 Spatial multiplex terminal selection metric calculation unit 3400 Scheduling unit 11100 Control device 11110 Center radio signal processing unit 11120 Transmission line IF
11200, 1120-1, 11200-2 Wireless device 11210 Transmission line IF
11220 Remote wireless signal processing unit 11230 Antenna unit

Claims (13)

A channel variation processing means that generates information for spatial multiplex terminal selection using channel estimates between wireless terminals and wireless devices, and
A transmission means for transmitting the spatial multiplex terminal selection information to the control device, and
A receiving means for receiving the scheduling information generated by using the spatial multiplex terminal selection information from the control device, and
Equipped with
The spatial multiplex terminal selection information is any one of the spatial multiplex terminal suppression information that suppresses the selection of the wireless terminal having a large channel fluctuation, the maximum number of spatial multiplex terminals, the terminal correlation value threshold value, and the terminal selection index correction value. Is
Wireless device. The channel variation processing means includes a channel variation information generation means and an information generation means for spatial multiplex terminal selection.
The channel variation information generation means generates channel variation information using the channel estimation value, and generates channel variation information.
The spatial multiplex terminal selection information generation means generates the spatial multiplex terminal selection information using the channel fluctuation information.
The wireless device according to claim 1 . A channel variation information generating means that generates channel variation information using a channel estimate between a wireless terminal and a wireless device,
A transmission means for transmitting the channel fluctuation information to the control device, and
A receiving means for receiving the scheduling information generated by using the spatial multiplex terminal selection information from the control device is provided.
The spatial multiplex terminal selection information is information calculated using the channel fluctuation information , and is spatial multiplex terminal suppression information that suppresses selection of the wireless terminal having a large channel fluctuation, a maximum number of spatial multiplex terminals, and a terminal correlation value. One of the threshold value and the terminal selection index correction value ,
Wireless device. The channel variation information is channel variation within the channel information averaging range of the frequency axis or the time axis.
The wireless device according to claim 2 or 3 . The scheduling information is information that spatially multiplexes the allocated resources to a plurality of terminals.
The wireless device according to any one of claims 1 to 4 . Physically separated from the control device and connected via a transmission line.
The wireless device according to any one of claims 1 to 5 . The wireless terminal communicates with the wireless device or communicates with other wireless devices .
The wireless device according to any one of claims 1 to 6 . A receiving means for receiving the spatial multiplex terminal selection information generated by using the channel estimation value between the wireless terminal and the wireless device from the wireless device, and
Scheduling means for generating terminal scheduling information using the spatial multiplex terminal selection information, and
A transmission means for transmitting the scheduling information to the wireless device, and
Equipped with
The spatial multiplex terminal selection information is any one of the spatial multiplex terminal suppression information that suppresses the selection of the wireless terminal having a large channel fluctuation, the maximum number of spatial multiplex terminals, the terminal correlation value threshold value, and the terminal selection index correction value. Is
Control device. A receiving means for receiving the channel variation information generated by using the channel estimation value between the wireless terminal and the wireless device from the wireless device, and
An information generation means for spatial multiplex terminal selection that generates spatial multiplex terminal selection information using the channel fluctuation information, and an information generation means for spatial multiplex terminal selection.
Scheduling means for generating terminal scheduling information using the spatial multiplex terminal selection information, and
A transmission means for transmitting the scheduling information to the wireless device, and
Equipped with
The spatial multiplex terminal selection information is any one of the spatial multiplex terminal suppression information that suppresses the selection of the wireless terminal having a large channel fluctuation, the maximum number of spatial multiplex terminals, the terminal correlation value threshold value, and the terminal selection index correction value. Is
Control device. The channel variation information is channel variation within the channel information averaging range of the frequency axis or the time axis.
The control device according to claim 9 . The scheduling information is information that spatially multiplexes the allocated resources to a plurality of terminals.
The control device according to any one of claims 8 to 10 . Physically separated from the wireless device and connected via a transmission line.
The control device according to any one of claims 8 to 11 . The wireless terminal communicates with the wireless device or communicates with other wireless devices .
The control device according to any one of claims 8 to 12 .

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