Communication apparatus, communication control method, and computer program

[Object]Provided is a communication apparatus capable of effectively using resources in a case where transmission is performed with directional beams.[Solving Means]Provided is a communication apparatus including a control unit configured to change a setting of scan with a directional beam between beam groups each including a plurality of the directional beams, in which the control unit adjusts the setting of the scan with the directional beam of each of the beam groups depending on a status of an area that the beam group covers.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is based on PCT filing PCT/JP2018/018112, filed May 10, 2018, which claims priority to JP 2017-116562, filed Jun. 14, 2017, the entire contents of each are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a communication apparatus, a communication control method, and a computer program.

BACKGROUND ART

In the 3GPP (Third Generation Partnership Project), various techniques for improving the capacity of cellular systems have currently been studied in order to accommodate explosively increasing traffic. For example, PTL 1 discloses a technique whose object is to make it possible to achieve better reception quality in a case where transmission is performed with directional beams.

CITATION LIST

Patent Literature

SUMMARY

Technical Problem

It is desired to effectively use resources when transmission is performed with directional beams.

In view of this, the present disclosure proposes novel and enhanced communication apparatus, communication control method, and computer program capable of effectively using resources in a case where transmission is performed with directional beams.

Solution to Problem

According to the present disclosure, there is provided a communication apparatus including a control unit configured to change a setting of scan with a directional beam between beam groups each including a plurality of the directional beams, in which the control unit adjusts the setting of the scan with the directional beam of each of the beam groups depending on a status of an area that the beam group covers.

Further, according to the present disclosure, there is provided a communication control method including: changing, by a processor, a setting of scan with a directional beam between beam groups each including a plurality of the directional beams; and adjusting, by the processor, the setting of the scan with the directional beam of each of the beam groups depending on a status of an area that the beam group covers.

Further, according to the present disclosure, there is provided a computer program for causing a computer to execute: changing a setting of scan with a directional beam between beam groups each including a plurality of the directional beams; and adjusting the setting of the scan with the directional beam of each of the beam groups depending on a status of an area that the beam group covers.

Advantageous Effect of Invention

As described above, according to the present disclosure, there can be provided novel and enhanced communication apparatus, communication control method, and computer program capable of effectively using resources in a case where transmission is performed with directional beams.

Note that, the above-mentioned effect is not necessarily limited, and any effect described herein or other effects that may be grasped from the present specification may be provided in addition to the above-mentioned effect or instead of the above-mentioned effect.

DESCRIPTION OF EMBODIMENT

Now, a preferred embodiment of the present disclosure is described in detail with reference to the attached drawings. Note that, in the present specification and the drawings, components having substantially the same functional configurations are denoted by the same reference signs so that overlapped description is omitted.

Note that, the following items are described in order.

1. Embodiment of Present Disclosure1.1. Background1.2. Configuration Example and Operation Example

2. Application Example

1. Embodiment of Present Disclosure

Prior to detail description of an embodiment of the present disclosure, the background of the embodiment of the present disclosure is described.

As described above, in the 3GPP (Third Generation Partnership Project), various techniques for improving the capacity of cellular systems have currently been studied in order to accommodate explosively increasing traffic. With regard to the future wireless communication system (5G) that has been studied in the 3GPP, it is unlikely that a mechanism that steplessly changes a beam emitted by a base station to recreate a beam following a terminal can be provided. This is because calculation cost for recreating a new beam arises. Also in FD-MIMO in 3GPP Rel 13, there has been employed a method that creates beams emitted by a base station in every direction in advance, and selects a beam required for a terminal from the beams created in advance to provide the beam. Such beams are called “codebook based beamforming.” To prepare beams at every degree from 0° to 360° in the horizontal direction, 360 types of beams are required. In a case where the beams overlap each other by half, 720 beams, which is twice as many as 360, satisfactorily serve as codebook based beams in the horizontal direction. In addition, in a case where beams at every degree from 0° to 180° in the vertical direction that overlap each other by half are prepared, 360 beams can cover an angle of 180° from −90° to +90° with the horizontal direction being 0°.

A quite large number of antenna elements, such as 256 (frequency band: 30 GHz) or 1,000 (frequency band: 70 GHz) antenna elements, can be mounted on base stations in the future. When the number of antenna elements increases in this way, very sharp beams can be created through beamforming processing using the antennas. For example, a very sharp beam having a half-value width (indicating the minimum degree at which a gain drops by 3 dB) of 1° or less can be provided from a base station to a terminal.

In order to establish communication between a base station and a terminal, it is necessary to determine what kinds of beams are to be used in the base station. In the case of downlink (DL) communication, it is necessary to determine DL beams to be provided by the base station. Further, in the case of uplink (UL) communication, it is necessary to determine UL beams that the base station is to use in reception. The UL beam, which is the latter, does not mean that the base station transmits radio waves, but means that an antenna that allows the base station to receive radio waves has directivity that is a beam.

By sweeping a plurality of beam candidates from a base station (beam sweeping), a terminal observing the beam candidates can determine, of the beams that the base station may use, a beam that the terminal easily receives. Meanwhile, when the terminal transmits a UL RS (Reference Signal) and the base station receives the RS while performing beam sweeping, the base station can determine a reception beam optimal for reception of the signal from the terminal.

FIG. 1is an example of a base station in a case where only digital units serve as antenna weights in beamforming. The configuration in which only digital units serve as antenna weights in beamforming as described above is called “full-digital antenna architecture.” In the case of the full-digital antenna architecture, when Tx sweeping (transmission sweeping) is performed, as many different resources as beams are required. Meanwhile, when Rx sweeping (reception sweeping) is performed, all beams can be simultaneously received in one resource. Thus, in the full-digital antenna architecture, the number of resources in reception sweeping can be small. That is, when full-digital reception sweeping is performed in the base station, a terminal only needs to transmit a UL RS (Resource Signal) corresponding to one resource, and thus consumes electric power a little. “Resource” used herein means an orthogonal resource using a frequency or time. For example, a resource block or resource element of LTE corresponds to “resource” used herein.

FIG. 2is an example of the base station in a case where phase shifters of analog units are included in beamforming. The configuration in which phase shifters of analog units are included in beamforming is called “digital-analog hybrid antenna architecture.” The digital-analog hybrid antenna architecture inFIG. 2includes the smaller number of digital units, each of which is hardware, and is thus advantageous in terms of cost. In the hybrid antenna architecture, however, the phase shifter connected to an antenna can only emit a beam in one direction, with the result that as many resources as the number of beams are required in transmission sweeping and reception sweeping. This means that, in order to perform reception sweeping by the base station, a terminal is required to transmit UL RSs to all resources corresponding to the number of beams. The terminal consequently consumes a large amount of electric power.

In light of the actual usage situation, it is assumed that the hybrid architecture illustrated inFIG. 2is used. How to overcome a flaw of the hybrid architecture that different beams require different frequency or time resources is therefore important.

If beams at every degree from 0° to 360° in the horizontal direction are prepared and beam sweeping is performed with the use of 360 resources to evaluate the beam one by one, the processing takes long time, the number of required resources is large, and a terminal consumes a large amount of electric power. The following technology is accordingly conceivable: a base station creates rough beams at every 10°, finds an optimal beam from the beams having a resolution of 10° by using 36 resources, and thereafter performs beam sweeping using accurate beams at every degree in the range of 10°, to thereby find an optimal beam. In this case, the base station can determine an optimal beam by using 36+10=46 resources, and hence the number of resources can be greatly reduced from 360 to 46.FIG. 3is an explanatory diagram illustrating an example of beam sweeping using rough beams. Further,FIG. 4is an explanatory diagram illustrating an example of beam sweeping using accurate beams. The base station may bundle plural accurate beams to use the accurate beams simultaneously, thereby treating the accurate beams as a rough beam. In that case, for example, plural (for example, three) adjacent accurate beams are simultaneously used as a rough beam. The base station may provide a bundle of three accurate beams as illustrated inFIG. 6to create a rough beam illustrated inFIG. 5. The three beams inFIG. 6that are transmitted at the same time and the same frequency can achieve a rough beam similar to the one inFIG. 5.

(Beam Sweeping from Plural Base Stations)

In a case where there are plural base stations around a terminal, it is necessary to determine transmission beams and reception beams of the plural base stations for the terminal.FIG. 7is an explanatory diagram illustrating an example of a case where there are plural base stations around a terminal. In the example illustrated inFIG. 7, an optimal beam for a terminal10is a beam2aof a base station1a, a beam2bof a base station1b, and a beam2cof a base station1c. As a method of determining an optimal beam, the following method is conceivable: of the plural base stations1ato1c, a base station closest to the terminal10or a main base station eventually determines an optimal beam on the basis of information from the terminal10, and instructs other base stations. In this case, a certain base station is required to determine transmission beams and reception beams of plural base stations, and hence a burden on the terminal increases.

“Channel reciprocity” means that a UL channel and a DL channel between a base station and a terminal are the same. In TDD (Time Division Duplex) systems, since the same frequency band is used for ULs and DLs, channel reciprocity of ULs and DLs is basically held. It is, however, necessary to perform the operation of calibration to make the base station and analog units of the terminal have the same TX/RX characteristics so that reciprocity is held in both channels to the analog units of the terminal and space.

With this channel reciprocity held, when the terminal selects a DL beam from the base station and notifies the number of the beam to the base station, a UL beam that the base station is to use can be determined without the operation of reception sweeping. A combination of rough beams and accurate beams, which is described in the (Beam Sweeping Efficiency) section above, is made as follows.

FIG. 8is an explanatory diagram illustrating an example of a DL beam sweeping process by the base station and the terminal. First, the base station performs transmission sweeping using a rough beam on the terminal (Step S11). This transmission sweeping is performed with a sweeping pattern unique to the base station. In other words, transmission sweeping is base station-specific or cell specific.

The terminal reports the number of a rough beam desired for the terminal in question to the base station (Step S12). The terminal determines the desired rough beam on the basis of whether a beam has the largest reception electric power, for example.

When receiving the report of the number of the rough beam from the terminal, the base station performs transmission sweeping using accurate beams corresponding to the rough beam (Step S13). Transmission sweeping at this time may employ a sweeping pattern unique to the terminal, which has been specially prepared for the terminal. Alternatively, a sweeping pattern common to all terminals may be prepared, and the base station may notify each terminal of a portion to monitor. In the former case, the transmission sweeping pattern itself is unique to the terminal (UE specific). In the latter case, it may be said that the settings of the transmission sweeping pattern are unique to the terminal (UE specific).

The terminal reports the number of an accurate beam desired for the terminal in question to the base station (Step S14). The terminal determines the desired accurate beam on the basis of whether a beam has the largest reception electric power, for example.

When receiving the report of the number of the accurate beam from the terminal, the base station transmits DL user data to the terminal by using the accurate beam (Step S15). Then, in a case where channel reciprocity is supposed to be held, the base station uses the same accurate beam as the accurate beam for transmission to receive UL user data from the terminal (Step S16).

When the beam sweeping process described above has been complete, an optimal transmission beam of the base station that is used between the base station and the terminal can be determined. DL CQI acquisition is grasping a channel quality and an interference status when the determined transmission beam is used. DL CQI acquisition is required for the terminal to notify, by using a feedback using a UL, which is called “CQI (Channel Quality Indicator) feedback,” the base station of a modulation method and a coding rate that the terminal wants the base station to use in DL data transmission. This feedback is performed as follows: the base station transmits a DL reference signal to the terminal for DL CQI acquisition, and the terminal receives the DL reference signal for DL CQI acquisition to evaluate a channel status. With this, the terminal can determine a desired CQI (combination of modulation method and coding rate).

As described above, it is necessary that the base station first determine a desired transmission beam in the beam sweeping process, and the terminal determine a CQI in the CQI acquisition procedure and notify the CQI to the base station as a CQI feedback.

When a base station configured to execute the beam sweeping process as described above does not have a particular target terminal and uniformly provides rough beams in all directions, the base station wastes resources. It is accordingly necessary to achieve a further reduction in resource.

In view of the points described above, the discloser of the subject application has made an intensive study on a technology that can further reduce resources that are used in executing the beam sweeping process. As a result, the discloser of the subject application has devised the technology that can further reduce resources that are used in executing the beam sweeping process, which is described later.

1.2. Configuration Example and Operation Example

First, with reference to the drawings, the schematic configuration of a system according to the embodiment of the present disclosure is described.FIG. 9is an explanatory diagram illustrating an example of the schematic configuration of the system according to the embodiment of the present disclosure. With reference toFIG. 9, the system according to the embodiment of the present disclosure includes a base station100and a terminal apparatus200. A system1is a system conforming to LTE, LTE-Advanced, or the fifth-generation mobile communication system (5G), or a communication standard equivalent thereto, for example.

The base station100performs wireless communication with the terminal apparatus200. For example, the base station100performs wireless communication with the terminal apparatus200positioned in a cell101of the base station100.

In the embodiment of the present disclosure, in particular, the base station100performs beamforming. For example, the beamforming in question is large-scale MIMO beamforming. The beamforming in question may also be called “massive MIMO beamforming,” “free dimension MIMO beamforming,” or “three-dimensional beamforming.” Specifically, for example, the base station100includes a directional antenna usable in large-scale MIMO, and multiplies a weight set for the directional antenna in question to a transmission signal, to thereby perform large-scale MIMO beamforming.

The terminal apparatus200performs wireless communication with the base station100. For example, the terminal apparatus200performs wireless communication with the base station100in a case of being positioned in the cell101of the base station100.

Subsequently, with reference toFIG. 10andFIG. 11, examples of the configurations of the base station100and the terminal apparatus200are described.

First, with reference toFIG. 10, the example of the configuration of the base station100according to the embodiment of the present disclosure is described.FIG. 10is a block diagram illustrating the example of the configuration of the base station100according to the embodiment of the present disclosure. With reference toFIG. 10, the base station100includes an antenna unit110, a wireless communication unit120, a network communication unit130, a storage unit140, and a processing unit150.

The antenna unit110emits, to space, signals output by the wireless communication unit120as radio waves. Further, the antenna unit110converts radio waves in space to signals, and outputs the signals in question to the wireless communication unit120.

For example, the antenna unit110includes a directional antenna. For example, the directional antenna in question is a directional antenna usable in large-scale MIMO.

The wireless communication unit120transmits and receives signals. For example, the wireless communication unit120transmits downlink signals to the terminal apparatus200, and receives uplink signals from the terminal apparatus200.

The network communication unit130transmits and receives information. For example, the network communication unit130transmits information to another node and receives information from the another node. Examples of the another node in question include another base station and a core network node.

The storage unit140stores data and programs for operation of the base station100.

The processing unit150provides various functions of the base station100. The processing unit150includes an information acquisition unit151and a control unit153. Note that the processing unit150may further include components other than these components. That is, the processing unit150may perform operation other than operation of these components.

How the information acquisition unit151and the control unit153specifically operate is described in detail below.

Specifically, the information acquisition unit151acquires information transmitted from the terminal apparatus200, in particular, information regarding the reception status of beams transmitted by the base station100.

Further, the control unit153performs control on transmission of beams from the base station100and the settings of beam sweeping, for example.

Next, with reference to referenceFIG. 11, the example of the configuration of the terminal apparatus200according to the embodiment of the present disclosure is described.FIG. 11is a block diagram illustrating the example of the configuration of the terminal apparatus200according to the embodiment of the present disclosure. With reference toFIG. 11, the terminal apparatus200includes an antenna unit210, a wireless communication unit220, a storage unit230, and a processing unit240.

The antenna unit210emits, to space, signals output by the wireless communication unit220as radio waves. Further, the antenna unit210converts radio waves in space to signals, and outputs the signals in question to the wireless communication unit220.

The wireless communication unit220transmits and receives signals. For example, the wireless communication unit220receives downlink signals from the base station100, and transmits uplink signals to the base station100.

The storage unit230stores data and programs for operation of the terminal apparatus200.

The processing unit240provides various functions of the terminal apparatus200. The processing unit240includes an information acquisition unit241and a control unit243. Note that the processing unit240may further include components other than these components. That is, the processing unit240may perform operation other than operation of these components.

How the information acquisition unit241and the control unit243specifically operate is described in detail below.

Subsequently, how the base station100specifically operates is described. When executing the beam sweeping process, the base station100according to the embodiment of the present disclosure forms groups each including a plurality of beams, and executes beam sweeping for each group. The numbers of beams of the groups may be different from each other. Further, the base station100may form beam groups with beams provided by a plurality of antenna panels.

FIG. 12is an explanatory diagram illustrating the base station100forming groups each including a plurality of beams.FIG. 12illustrates three Beam Groups 1, 2, and 3. In the example illustrated inFIG. 12, Beam Group 1 includes 13 beams, and Beam Groups 2 and 3 each include three beams. As a matter of course, the number of beams of the beam group is not limited to the example.

When forming a group including a plurality of beams, the base station100may form a group including beams provided by a plurality of the base stations100.FIG. 13is an explanatory diagram illustrating base stations100aand100bforming groups each including a plurality of beams.FIG. 13illustrates three Beam Groups 1, 2, and 3. In the example illustrated inFIG. 13, Beam Group 1 includes 13 beams from the base station100aand 13 beams from the base station100b, and Beam Groups 2 and 3 each include three beams from the base station100a. As a matter of course, the number of beams of the beam group is not limited to the example.

The base station100performs beam sweeping in the unit of each beam group. The base station100changes the settings of beam sweeping, for example, the number of beams or the frequency of beam sweeping, between the beam groups. The base station100provides, for each beam group, a resource location thereof. The base station100provides the resource location with, for example, system information that is a broadcast signal or a dedicated signal for each terminal. When changing the settings of beam sweeping between the beam groups, the base station100may change the settings of beam sweeping depending on the status of an area that the beam group covers, for example, the number of the terminal apparatuses200. For example, when there are a lot of terminal apparatuses200, the base station100may change the settings of beam sweeping so that beam sweeping with a beam group covering the area is performed frequently.

In the example illustrated inFIG. 12, there are a lot of terminal apparatuses200in an area that the beams of Beam Group 1 cover. Meanwhile, there is only one terminal apparatus200in an area that the beams of Beam Group 1 cover, and there is no terminal apparatus200in an area that the beams of Beam Group 3 cover. Thus, the base station100sets, with respect to Beam Group 1, a time between the end of beam sweeping and the start of next beam sweeping that is shorter than those of the remaining beam groups. In contrast to this, the base station100sets, with respect to Beam Group 3 having no terminal apparatus200, a time between the end of beam sweeping and the start of next beam sweeping that is longer than those of the remaining beam groups.

FIG. 14is an explanatory diagram illustrating an example of timing of beam sweeping by the base station100.FIG. 14illustrates an example of timing of beam sweeping with Beam Groups 1, 2, and 3 illustrated inFIG. 12. The base station100sets, with respect to Beam Group 1, a time between the end of beam sweeping and the start of next beam sweeping that is shorter than those of the remaining beam groups, as illustrated inFIG. 14. Further, the base station100sets, with respect to Beam Group 3, a time between the end of beam sweeping and the start of next beam sweeping that is longer than those of the remaining beam groups, as illustrated inFIG. 14.

In a case where beam sweeping is performed with Beam Group 1, for example, with the use of different time or frequency resources, the base station100transmits 13 beams by using the respective resources at 13 beam transmission timings.FIG. 15is an explanatory diagram illustrating beam sweeping with Beam Group 1 by the base station100. That is, the base station100does not simultaneously provide data with the 13 beams, but performs beam sweeping like a lighthouse. Meanwhile, the beams belonging to Beam Groups 2 and 3 travel in greatly different directions from Beam Group 1 with respect to the base station100, and hence even when the beams belonging to Beam Groups 2 and 3 are transmitted with the use of completely the same time or frequency as Beam Group 1, the terminal apparatus200does not observes interference. A terminal that can observe the beams belonging to Beam Group 2 cannot observe the beams belonging to Beam Group 3 at all or can hardly observe the beams in question.FIG. 16is an explanatory diagram illustrating beam sweeping with Beam Groups 2 and 3 by the base station100. In this case, electric power provided to the beams belonging to Beam Group 2 and the beams belonging to Beam Group 3 is half of electric power provided to the beams belonging to Beam Group 1. The base station100notifies the terminal apparatus200of the value of electric power for each beam group in advance. When the base station100notifies the terminal apparatus200of the value of electric power for each beam group in advance, the base station100can fairly evaluate the beam quality of the beam groups, namely, Beam Groups 1, 2, and 3. Even when the base station100has grasped a difference in electric power between the groups, since the terminal apparatus200selects a limited preferable beam and reports information associated with the preferable beam to the base station100, the terminal apparatus200is required to grasp the difference in transmission electric power between the beam groups. In addition, when such a difference in electric power is notified for each beam, the amount of information to be notified is large. Thus, it is very important that the base station100notifies the difference in electric power for each beam group. This is because the number of beams is quite large.

The base station100adjusts an interval between the end of beam sweeping and the start of next beam sweeping with respect not only to beam sweeping using rough beams, but also to beam sweeping using accurate beams depending on the number of the terminal apparatuses200.

Table 1 is an example of information associated with the beam groups of which the terminal apparatus200is notified by the base station100. With such information of which the terminal apparatus200is notified by the base station100, the terminal apparatus200can appropriately evaluate the beams belonging to each beam group.

TABLE 1ItemsContentsA period in which all beamA period (such as 100 ms orgroups can be observed50 ms) and an offset. Theoffset is indicated by an. (System Frame Number).SFN is a number given to asynchronization period.Electric powerThis may be indicated by anindex number correspondingto -50 dBm, for example.
(Table 1: examples of information associated with a beam group)

FIG. 17is a flowchart illustrating operation examples of the base station100and the terminal apparatus200according to the embodiment of the present disclosure.FIG. 17illustrates operation examples when the terminal apparatus200determines an optimal beam from beams emitted by the base station100, and transmission or reception of data is performed between the base station100and the terminal apparatus200by beamforming. Now, the operation examples of the base station100and the terminal apparatus200according to the embodiment of the present disclosure are described with reference toFIG. 17.

The base station100first transmits schedule information regarding a rough beam group to the terminal apparatus200(Step S101). This schedule information is information indicating a time or frequency resource location of beams belonging to the rough beam group.

Subsequently, the base station100performs transmission sweeping using the rough beams in a beam group unit on the terminal apparatus200on the basis of the schedule information regarding the rough beam group, which has been transmitted in Step S101(Step S102). This transmission sweeping is performed with a sweeping pattern unique to the base station. In other words, the transmission sweeping is base station-specific or cell specific.

The terminal apparatus200reports the number of a rough beam desired for the terminal apparatus200to the base station100(Step S103). The terminal apparatus200determines the desired rough beam on the basis of whether or not a beam has the largest reception electric power, for example.

When receiving the report of the number of the rough beam from the terminal apparatus200, the base station100transmits, to the terminal apparatus200, schedule information regarding an accurate beam group corresponding to the rough beam (Step S104). This schedule information is information indicating a time or frequency resource location of beams belonging to the accurate beam group.

Subsequently, the base station100performs, on the terminal apparatus200, transmission sweeping using the accurate beams in a beam group unit on the basis of the schedule information regarding the accurate beam group, which has been transmitted in Step S104(Step S105). Transmission sweeping at this time may employ a sweeping pattern unique to the terminal, which has been specially prepared for the terminal. Alternatively, a sweeping pattern common to all terminals may be prepared, and the base station may notify each terminal of a portion to monitor. In the former case, the transmission sweeping pattern itself is unique to the terminal (UE specific). In the latter case, the settings of the transmission sweeping pattern are unique to the terminal (UE specific).

The terminal apparatus200reports the number of an accurate beam desired for the terminal apparatus200to the base station100(Step S106). The terminal apparatus200determines the desired accurate beam on the basis of whether or not a beam has the largest reception electric power, for example.

When receiving the report of the number of the accurate beam from the terminal apparatus200, the base station100transmits DL user data to the terminal by using the accurate beam (Step S107). Then, in a case where channel reciprocity is supposed to be held, the base station100uses the same accurate beam as the accurate beam for transmission to receive data from the terminal, and thus receives UL user data from the terminal apparatus200(Step S108).

The base station100according to the embodiment of the present disclosure groups the beams and performs beam sweeping in a group unit in this way, thereby being capable of achieving beam sweeping efficiently using resources.

FIG. 13illustrates the base stations100aand100bforming the groups each including the plurality of beams. That is, Beam Group 1 includes 26 beams in total from the base stations100aand100b. With beam grouping across the base stations, the terminal apparatus200can efficiently observe the beams provided by the plurality of base stations.

In the present embodiment, the beam groups can be formed with the use of a plurality of beams provided by the plurality of base stations100or beams provided by a plurality of antenna panels. With the beams from the plurality of base stations100or the plurality of antenna panels grouped into one beam group in this way, the terminal apparatus200observes the beams in continuous time, and hence the terminal apparatus200can have operating time without interruption. Thus, when not performing the beam observation operation, the terminal apparatus200can enter a mode consuming electric power a little, for example, which can lead to a reduction in power consumption.

In a case where there are plural, for example, five base stations100, the terminal apparatus200is required to observe beam sweeping by the different base stations100in different five time periods. This increases a burden on the terminal apparatus200. Meanwhile, the technique that groups beams from the plural base stations100or plural antenna panels into one beam group is more effective in sweeping using accurate beams than in sweeping using rough beams. When the plural base stations100transmits beams to the terminal apparatus200in cooperation with each other in continuous time, a burden on the terminal apparatus200can be reduced.

FIG. 18is a flowchart illustrating operation examples of the base stations100aand100band the terminal apparatus200according to the embodiment of the present disclosure.FIG. 18illustrates operation examples when the terminal apparatus200determines an optimal beam from beams emitted by the base stations100aand100b, and transmission or reception of data is performed between the terminal apparatus200and the base stations100aand100bby beamforming. Now, the operation examples of the base stations100aand100band the terminal apparatus200according to the embodiment of the present disclosure are described with reference toFIG. 18.

The base station100afirst performs transmission sweeping using rough beams in a beam group unit on the basis of schedule information regarding a rough beam group that has been provided to the terminal apparatus200in advance (Step S111).

The terminal apparatus200reports the number of a rough beam desired for the terminal apparatus200to the base station100a(Step S112). The terminal apparatus200determines the desired rough beam on the basis of whether or not a beam has the largest reception electric power, for example.

When beam sweeping by the base station100ais finished, the base station100bconfigured to emit beams belonging to the same beam group subsequently performs transmission sweeping using the rough beams in a beam group unit on the basis of schedule information regarding the rough beam group that has been provided to the terminal apparatus200in advance (Step S113).

The terminal apparatus200reports the number of a rough beam desired for the terminal apparatus200to the base station100b(Step S114). The terminal apparatus200determines the desired rough beam on the basis of whether or not a beam has the largest reception electric power, for example.

When beam sweeping by the base station100bis finished, the base station100aforms, when providing a plurality of accurate beams to the base station100b, a beam group including the plurality of accurate beams (referred to as “Beam Group 3”). The base station100anotifies, in order to form the beam group, the base station100bof a request and a resource location of the beam group (Step S115). In a case of responding to the request from the base station100a, the base station100bsends back ACK (Step S116).

The base station100athat has received ACK from the base station100bnotifies the terminal apparatus200of a time or frequency resource location of Beam Group 3 (Step S117). The base stations100aand100bform Beam Group 3 in cooperation with each other by using the scheduled time or frequency resource, to thereby perform beam sweeping with the accurate beams (Step S118).

The terminal apparatus200reports the number of an accurate beam desired for the terminal apparatus200to the base station100a(Step S119). The terminal apparatus200determines the desired accurate beam on the basis of whether or not a beam has the largest reception electric power, for example.

When receiving the report of the number of the accurate beam from the terminal apparatus200, the base station100transmits DL user data to the terminal by using the accurate beam (Step S120). Then, in a case where channel reciprocity is supposed to be held, the base station100uses the same accurate beam as the accurate beam for transmission to receive data from the terminal, and thus receives UL user data from the terminal apparatus200(Step S121).

The terminal apparatus200operates in this way, thereby being capable of observing the accurate beams from the plurality of base stations by observing only one location. To achieve this, a concept of beam groups formed by a plurality of base stations is important. In the operation examples illustrated inFIG. 18, the terminal apparatus200can receive beam sweeping with the beam group formed by the base stations100aand100b, and also receive, at another time, beam sweeping with a beam group formed by another base station. Thus, according to the embodiment of the present disclosure, in a case where the number of base stations related to the terminal apparatus200increases, a burden on the terminal apparatus200can be reduced.

As described above, the beam group can not only be a group of beams in the same base station, but also be a group of beams from a plurality of base stations. The above-mentioned effect is obtained through grouping of beams from a plurality of base stations. Specifically, a burden on the terminal apparatus200is smaller in a case where the terminal apparatus200sets beams from a plurality of base stations as one group and observes beam sweeping with the beam group than in a case where the terminal apparatus200monitors the beams from the base stations one by one to determine an appropriate beam. Meanwhile, in a case where there are a plurality of base stations or a case where a plurality of antenna panels is mounted on a base station, the number of beam groups is predicted to increase, and how long the terminal apparatus200is required to monitor beam sweeping to observe whole beam sweeping is unknown.

Accordingly, the base station100notifies the terminal of a beam group that the terminal apparatus200is to observe or the period of a plurality of beam groups and the start time of beam sweeping with the beam groups. The period is a period longer than a period in which a synchronization signal is being provided, for example, 5 milliseconds or 10 milliseconds. The terminal apparatus200observes beams of the plurality of target beam groups during the period. With beam observation in the specified period, the terminal apparatus200positively observes all the beams from the base station100.

FIG. 19is a flowchart illustrating operation examples of the base station100and the terminal apparatus200according to the embodiment of the present disclosure.FIG. 19illustrates operation examples when the terminal apparatus200determines an optimal beam from beams emitted by the base station100, and transmission or reception of data is performed between the base station100and the terminal apparatus200by beamforming. Now, the operation examples of the base station100and the terminal apparatus200according to the embodiment of the present disclosure are described with reference toFIG. 19.

The base station100notifies the terminal apparatus200of information regarding the maximum period and an offset or the maximum period or the offset (Step S131). Table 2 is an example of information of which the terminal apparatus200is notified by the base station100.

TABLE 2ItemsContentsA period in which all beamExample: 500 msgroups can be observedThe beginning of the aboveExample: system frameperiod (offset)number = 10(SFN is specified by anumber given to asynchronization period)
(Table 2: examples of information associated with a beam group)

The subsequent operation is similar to the one illustrated inFIG. 17. That is, the base station100first transmits schedule information regarding a rough beam group to the terminal apparatus200(Step S132). Subsequently, the base station100performs, on the terminal apparatus200, transmission sweeping using the rough beams in a beam group unit on the basis of the schedule information regarding the rough beam group, which has been transmitted in Step S132(Step S133). At this time, the terminal apparatus200observes the beams by using the information transmitted from the base station100in Step S131. Then, the terminal apparatus200reports the number of a rough beam desired for the terminal apparatus200to the base station100(Step S134).

When receiving the report of the number of the rough beam from the terminal apparatus200, the base station100transmits, to the terminal apparatus200, schedule information regarding an accurate beam group corresponding to the rough beam (Step S135). Subsequently, the base station100performs, on the terminal apparatus200, transmission sweeping using the accurate beams in a beam group unit on the basis of the schedule information regarding the accurate beam group, which has been transmitted in Step S135(Step S136). At this time, the terminal apparatus200observes the beams by using the information transmitted from the base station100in Step S131.

The terminal apparatus200reports the number of an accurate beam desired for the terminal apparatus200to the base station100(Step S137). When receiving the report of the number of the accurate beam from the terminal apparatus200, the base station100transmits DL user data to the terminal by using the accurate beam (Step S138). Then, in a case where channel reciprocity is supposed to be held, the base station100uses the same accurate beam as the accurate beam for transmission to receive data from the terminal, and thus receives UL user data from the terminal apparatus200(Step S139).

With the base station100notifying the terminal apparatus200of the maximum period of beam sweeping, the terminal apparatus200positively monitors all the beam groups by monitoring beams in the period. What is important here is that the period information that the base station100provides is associated with neither a beam period nor a beam group period, but is associated with a period that allows the terminal apparatus200to observes a plurality of beams or beam groups completely by observing the beams or beam groups in the time interval.

In the case of UE specific beam groups, since the base station100specifies a direction in which the terminal apparatus200is to monitor beam groups, a burden on the terminal apparatus200is small. In a case where there is a plurality of cell specific beam groups, however, when there is no information regarding which beam group is to be referred to, the terminal apparatus200observes beam sweeping belonging to all beam groups even though there is no need for the terminal apparatus200to monitor all the beam groups.

Accordingly, the terminal apparatus200receives information regarding not only the period but also which beam group is to be referred to from the base station100, thereby being capable of observing beam sweeping with a specific beam group instead of observing beam sweeping belonging to all the beam groups.

In order to allow the terminal apparatus200to freely select a beam group to monitor, the base station100notifies the terminal apparatus200of the details of beam group information. The base station100does not notify information regarding each beam, but provides information regarding each beam group, which is a bundle of beams. With provision of the information regarding each beam group, the terminal apparatus200can reduce electric power consumed for reception to the minimum necessity. The base station100can notify the terminal apparatus200of the beam group information with system information. In the flowchart ofFIG. 19, the base station100may notify the terminal apparatus200of the beam group information in Step S131. Table 3 is an example of beam group information of which the terminal apparatus200is notified by the base station100.

TABLE 3ItemsContentsBeam group IDIdentification for specifying a beamgroupLayerRough beam/accurate beamBaseBase stations from which a beam groupstation/TRPhas been transmittedIn a case where a beam group has beentransmitted from one base station, theone base station is describedIn a case where a beam group isformed by a plurality of base stations,the plurality of base stations isdescribedIn the case where a beam group isformed by a plurality of base stations,which station provides which beam canalso be describedExample 1: Base Station 1Example 2: Base Station 1, Base Station2, and Base Station 3Example 3: Base Station 1: Beam 1 toBeam 3, Base Station 2: Beam 4 to Beam9, and Base Station 3: Beam 10 to Beam13Panel numberPanels of a base station from which abeam group has been transmittedHigh-speedTo be monitored by a high-speedmovementterminalLow-speedTo be monitored by a low-speed or fixedmovementterminalUse caseTo be monitored by a terminalsupporting low latency communication/tobe monitored by a terminal supportingnormal communication/to be monitored byan MTC terminal
(Table 3: examples of information associated with a beam group)

A technology that allows a plurality of terminals to simultaneously receive downlink data at the same frequency and the same time is called “downlink multi user MIMO (DL MU-MIMO).” What is important in performing DL MU-MIMO is to determine which combination of terminals is used to perform MU-MIMO. This is called “terminal pairing.” In this pairing, it is important that a beam appropriate for a terminal A does not serve as an interference source for another terminal B (the terminal B can hardly receive the beam), and vice versa. It is important that a beam appropriate for the terminal B does not serve as an interference source for the terminal A. It is important that when forming a beam group, a base station forms the beam group including beams for the terminal A and the terminal B, which are different from each other. The beam group serves as a beam group for the terminal A and the terminal B. When the base station does not specify how the terminal A and the terminal B each evaluate the beam group, however, the terminal A cannot determine which beam preferably has high electric power and which beam preferably has low electric power.

Accordingly, the base station100according to the present embodiment notifies the terminal apparatus200of, of the plurality of beam groups, which beam group is for desired beam selection and which beam group serves as an interference signal for beam evaluation. Table 4 is an example of beam group information of which the terminal apparatus200is notified by the base station100.

TABLE 4Beam groupnumberContents1Desired signal (select beam havinglarge reception electric power)2Desired signal (select beam havinglarge reception electric power)3Interference signal (select beam havinglarge reception electric power)4Interference signal (select beam havingsmall reception electric power)5Interference signal (select two beamshaving large reception electric powerand three beams having smallinterference electric power)
(Table 4: examples of information associated with a beam group)

In Table 4, in the parentheses in the “Contents” column, examples of how the terminal apparatus200uses the contents are described. The base station100may or may not include the information in the parentheses in the information of which the terminal apparatus200is notified.

Further, the base station100notifies the terminal apparatus200of, in one beam group to be provided, which beam is for desired beam selection and which beam serves as an interference signal for beam evaluation. Table 5 is an example of beam group information of which the terminal apparatus200is notified by the base station100.

TABLE 5Beam numberContents1 to 5Desired signal5 to 13Interference signal
(Table 5: examples of information associated with beams in a beam group)

The terminal apparatus200selects, as desired signals and interference signals, signals having large reception electric power. A beam having the largest reception electric power in the desired signal is a desired beam. A beam having the largest reception electric power in the interference signal indicates that the interference signal is largest.

The terminal apparatus200evaluates the beam groups in this way, thereby being capable of calculating SINR (signal-to-interference-plus-noise ratio) in consideration of MU-MIMO pairing to provide, to the base station100, feedback about receivable modulation method and encoding rate, and channel quality information.

Even when the terminal apparatus200does not send back channel quality information to the base station100, the terminal apparatus200can collect information for MU-MIMO pairing with the beam groups or by clarifying desired beams and interference beams in a beam group. The terminal apparatus200notifies the base station100of the collected information. The base station100can efficiently perform pairing of the terminal measure200by using the information transmitted from the terminal apparatus200.

In the example descried above, it is assumed that the base station100provides beam sweeping with the beam groups periodically. The following case is, however, conceivable: it is preferred that the base station100dynamically change, for example, the period of beam sweeping with the beam groups. In a case where a location of a beam group is specified with system information, RRC signaling, or another downlink control signal, the settings of beam groups are changed in a semi-static manner, and hence such methods cannot be used to dynamically change the settings. Accordingly, a concept of system information regarding each beam group (beam group system information) is introduced.

Thus, the base station100provides, in a beam group, information regarding the beam group. Specifically, the base station100provides, as information regarding a beam group, information common to a plurality of beams belonging to the beam group and information regarding each beam belonging to the beam group. The information common to a plurality of beams belonging to the beam group is a resource location to which the beam group is transmitted next. This resource location is notified with a time resource and a frequency resource. The information regarding each beam belonging to the beam group is information regarding transmission electric power of each beam and whether or not each beam is an interference source. The information given above is an example, and what is important is that information regarding a beam group and information regarding beams belonging to the beam group are provided as beam group system information with the use of the beams belonging to the beam group. In general, system information is provided as base station or cell information, but in the present embodiment, as system information regarding a beam group that is a bundle of beams, the system information is provided with the beam group.

It is assumed that beams belonging to a beam group are provided to the terminal apparatus200by beam sweeping at different times. In such a case, the terminal apparatus200monitoring the beam group cannot observe all the beams. Thus, all beams belonging to a certain beam group have the same beam group system information. With the beam group system information, all beams belonging to a certain beam group provide the same information.

How to reduce the overhead of resources that are used for beam sweeping is now considered. When performing beam sweeping four times, in the last beam sweeping, the base station100provides, to the terminal apparatus200, one set of a plurality of periods and offsets set in advance that the base station100is to take, with beam group system information provided by beam sweeping. The following are important: the period and the offset are not specified every beam sweeping and the information is provided once per several times of beam sweeping, and how information regarding which set of periods and offsets set in advance is to be taken is provided.

FIG. 20is an explanatory diagram illustrating an example of a beam group system information providing pattern by the base station100.FIG. 20illustrates an example in which beam group system information is provided once per three times of beam sweeping. Reference numeral301indicates the period of beam sweeping having information that is beam group system information. Reference numeral302indicates the period of beam sweeping not having information that is beam group system information. In a case where beam sweeping having information that is beam group system information is performed, the base station100has the beam group system information after a beam specific sequence. This sequence is a unique sequence such as an M-sequence, and sequences to be used for beams are different from each other. As part of beam sweeping that is performed three times, beam sweeping not having such beam group system information is performed twice. Thus, when performing beam sweeping three times, the base station100can provide beams for performing beam sweeping twice with fewer resources than a beam having the beam group system information.

FIG. 21is an explanatory diagram illustrating an example of a beam group system information providing pattern by the base station100. InFIG. 21, each block represents the period of beam sweeping with 13 beams. Further, each block represents beam sweeping with the same beam group.

Reference numeral301indicates, as inFIG. 20, beam sweeping having, in each of 13 beams, beam group system information that is information associated with the beam group after a beam specific sequence. Reference numeral302indicates, as inFIG. 20, beam sweeping only having a beam specific sequence and not having beam group system information. Resources required for beam sweeping indicated by reference numeral302are fewer than resources required for beam sweeping indicated by reference numeral301.

The base station100notifies the terminal apparatus200of four configurations in advance with RRC signaling or entire-cell system information in a semi-static manner as illustrated inFIG. 21. Then, the base station100specifies, with the beam group system information, a configuration to be used next from the four configurations set in advance. Configuration1is a setting that provides beam group system information once per five times of beam sweeping. Configuration2has the same period and provision frequency of beam group system information as Configuration1but a different offset. Configuration3is a setting that provides beam group system information once per three times of beam sweeping. Configuration4is a setting that provides beam group system information once per five times of beam sweeping, and has a longer period between beam sweeping and beam sweeping than Configuration1. The base station100dynamically selects one of the beam group configurations set in advance, thereby being capable of flexibly and dynamically changing the settings of beam sweeping. With this, the base station100can optimize resources that are used for beam sweeping, thereby being capable of reducing signaling overhead by beam sweeping. Further, the base station100can be expected to have enhanced throughput.

Note that, in the example described above, the base station100generates beam groups each including a plurality of directional beams and changes the settings of beam sweeping between the beam groups, but the present disclosure is not limited to the example. The terminal apparatus200may generate beam groups each including a plurality of directional beams in a similar manner. In such a case, the terminal apparatus200may execute the operation of changing the settings of beam sweeping between the beam groups as described above.

2. Application Example

The technology according to the present disclosure is applicable to various products. For example, the base station100may be realized as any type of eNB (evolved Node B) such as a macro eNB or a small eNB. A small eNB may be an eNB that covers a smaller cell than a macro cell, such as a pico eNB, a micro eNB, or a home (femto) eNB. Alternatively, the base station100may be realized as another type of base station such as a Node B or a BTS (Base Transceiver Station). The base station100may include a main body configured to control wireless communication (also referred to as “base station apparatus”) and one or more RRHs (Remote Radio Heads) disposed in a different place from the main body. Further, various types of terminals, which are described later, may operate as the base station100by temporarily or semi-permanently executing the base station function.

Further, for example, the terminal apparatus200may be realized as a mobile terminal such as a smartphone, a tablet PC (Personal Computer), a notebook computer, a portable game terminal, a portable/dongle type mobile router, or a digital camera, or an in-vehicle terminal such as a car navigation apparatus. Further, the terminal apparatus2200may be realized as a terminal configured to perform M2M (Machine To Machine) communication (also referred to as “MTC (Machine Type Communication) terminal”). In addition, the terminal apparatus2200may be a wireless communication module that is mounted on such a terminal (for example, an integrated circuit module including one die).

(Application Example of Base Station)

First Application Example

FIG. 22is a block diagram illustrating a first example of the schematic configuration of an eNB to which the technology according to the present disclosure may be applied. An eNB800includes one or more antennas810and a base station apparatus820. The antennas810may each be connected to the base station apparatus820through an RF cable.

The antennas810each include one or a plurality of antenna elements (for example, a plurality of antenna elements of a MIMO antenna), and are used when the base station apparatus820transmits or receives wireless signals. The eNB800may include the plurality of antennas810, as illustrated inFIG. 22. The plurality of antennas810may be compatible with a plurality of frequency bands used by the eNB800, for example. Note that, althoughFIG. 22illustrates the example in which the eNB800includes the plurality of antennas810, the eNB800may only include one antenna810.

The base station apparatus820includes a controller821, a memory822, a network interface823, and a wireless communication interface825.

The controller821may be, for example, a CPU or a DSP, and operates various functions of a higher layer of the base station apparatus820. For example, the controller821generates a data packet from data in signals processed by the wireless communication interface825, and transfers the generated packet via the network interface823. The controller821may bundle data from a plurality of baseband processors to generate a bundled packet, and transfer the generated bundled packet. Further, the controller821may have a logical function of executing control such as radio resource control, radio bearer control, mobility management, admission control, or scheduling. Further, the controller821may execute the control in question in corporation with a neighboring eNB or a core network node. The memory822includes a RAM and a ROM, and stores a program that is executed by the controller821, and various types of control data (for example, terminal list, transmission electric power data, and scheduling data).

The network interface823is a communication interface for connecting the base station apparatus820to a core network824. The controller821may communicate with a core network node or another eNB via the network interface823. In this case, the eNB800may be connected to a core network node or another eNB through a logical interface (for example, S1 interface or X2 interface). The network interface823may be a wired communication interface or a wireless communication interface for wireless backhaul. In a case where the network interface823is a wireless communication interface, the network interface823may use a higher frequency band for wireless communication than a frequency band used by the wireless communication interface825.

The wireless communication interface825supports any cellular communication scheme such as LTE (Long Term Evolution) or LTE-Advanced, and provides wireless connection to a terminal positioned in a cell of the eNB800via the antenna810. The wireless communication interface825may typically include, for example, a baseband (BB) processor826and an RF circuit827. The BB processor826may perform, for example, encoding/decoding, modulating/demodulating, and multiplexing/demultiplexing, to thereby execute various types of signal processing of layers (for example, L1, MAC (Medium Access Control), RLC (Radio Link Control), and PDCP (Packet Data Convergence Protocol)). The BB processor826may have a part or all of the above-mentioned logical functions instead of the controller821. The BB processor826may be a memory configured to store a communication control program, or a module including a processor configured to execute the program in question and related circuits. The functions of the BB processor826may be changed through updating of the program. Further, the module may be a card or blade that is inserted into a slot of the base station apparatus820. Alternatively, the module may be a chip that is mounted on the card or the blade. Meanwhile, the RF circuit827may include, for example, a mixer, a filter, and an amplifier, and transmits and receives wireless signals via the antenna810.

The wireless communication interface825may include the plurality of BB processors826, as illustrated inFIG. 22. The plurality of BB processors826may be compatible with a plurality of frequency bands used by the eNB800, for example. Further, the wireless communication interface825may include the plurality of RF circuits827, as illustrated inFIG. 22. The plurality of RF circuits827may correspond to a plurality of antenna elements, for example. Note that, althoughFIG. 22illustrates the example in which the wireless communication interface825includes the plurality of BB processors826and the plurality of RF circuits827, the number of the BB processors826or RF circuits827of the wireless communication interface825may be one.

In the eNB800illustrated inFIG. 22, one or more components in the base station100(for example, processing unit150), which are described with reference toFIG. 10, may be implemented by the wireless communication interface825. Alternatively, at least some of these components may be implemented by the controller821. As an example, the eNB800may have mounted thereon a module including a part of the wireless communication interface825(for example, BB processor826) or all components thereof, and/or the controller821, and the one or more components may be implemented by the module in question. In this case, the module may store a program for causing the processor to function as the one or more components (in other words, a program for causing the processor to execute operations of the one or more components), to thereby execute the program in question. As another example, the eNB800may have installed thereon the program for causing the processor to function as the one or more components, and the wireless communication interface825(for example, BB processor826) and/or the controller821may execute the program in question. As described above, the eNB800, the base station apparatus820, or the module may be provided as an apparatus including the one or more components, and the program for causing the processor to function as the one or more components may be provided. A readable recording medium having recorded thereon the program may also be provided.

Further, in the eNB800illustrated inFIG. 22, the wireless communication unit120described with reference toFIG. 10may be implemented by the wireless communication interface825(for example, RF circuit827). Further, the antenna unit110may be implemented by the antenna810. Further, an interface between the processing unit240and an upper node or another base station apparatus may be implemented by the controller821and/or the network interface823.

Second Application Example

FIG. 23is a block diagram illustrating a second example of the schematic configuration of an eNB to which the technology according to the present disclosure may be applied. An eNB830includes one or more antennas840, a base station apparatus850, and an RRH860. The antennas840may each be connected to the RRH860through an RF cable. Further, the base station apparatus850and the RRH860may be connected to each other through a high-speed line such as an optical fiber cable.

The antennas840each include one or a plurality of antenna elements (for example, a plurality of antenna elements of a MIMO antenna), and are used when the RRH860transmits or receives wireless signals. The eNB830may include the plurality of antennas840, as illustrated inFIG. 23. The plurality of antennas840may be compatible with a plurality of frequency bands used by the eNB830, for example. Note that, althoughFIG. 23illustrates the example in which the eNB830includes the plurality of antennas840, the eNB830may include one antenna840.

The wireless communication interface855supports any cellular communication scheme such as LTE or LTE-Advanced, and provides wireless communication to a terminal positioned in a sector corresponding to the RRH860via the RRH860and the antenna840. The wireless communication interface855may typically include, for example, a BB processor856. The BB processor856is similar to the BB processor826described with reference toFIG. 22, except that the BB processor856is connected to the RF circuit864of the RRH860via the connection interface857. The wireless communication interface855may include the plurality of BB processors856, as illustrated inFIG. 23. The plurality of BB processors856may be compatible with a plurality of frequency bands used by the eNB830, for example. Note that, althoughFIG. 23illustrates the example in which the wireless communication interface855includes the plurality of BB processors856, the wireless communication interface855may only include one BB processor856.

The connection interface857is an interface for connecting the base station apparatus850(wireless communication interface855) to the RRH860. The connection interface857may also be a communication module for communication in the high-speed line that connects the base station apparatus850(wireless communication interface855) to the RRH860.

Further, the RRH860includes a connection interface861and a wireless communication interface863.

The connection interface861is an interface for connecting the RRH860(wireless communication interface863) to the base station apparatus850. The connection interface861may also be a communication module for communication in the high-speed line.

The wireless communication interface863transmits and receives wireless signals via the antenna840. The wireless communication interface863may typically include, for example, the RF circuit864. The RF circuit864may include, for example, a mixer, a filter, and an amplifier, and transmits and receives wireless signals via the antenna840. The wireless communication interface863may include the plurality of RF circuits864, as illustrated inFIG. 23. The plurality of RF circuits864may correspond to a plurality of antenna elements, for example. Note that, althoughFIG. 23illustrates the example in which the wireless communication interface863includes the plurality of RF circuits864, the wireless communication interface863may include one RF circuit864.

In the eNB830illustrated inFIG. 23, one or more components in the base station100(for example, processing unit140), which are described with reference toFIG. 10, may be implemented by the wireless communication interface855and/or the wireless communication interface863. Alternatively, at least some of these components may be implemented by the controller851. As an example, the eNB830may have mounted thereon a module including a part of the wireless communication interface855(for example, BB processor856) or all components thereof, and/or the controller851, and the one or more components may be implemented by the module in question. In this case, the module may store a program for causing the processor to function as the one or more components (in other words, a program for causing the processor to execute operations of the one or more components), to thereby execute the program in question. As another example, the eNB830may have installed thereon the program for causing the processor to function as the one or more components, and the wireless communication interface855(for example, BB processor856) and/or the controller851may execute the program in question. As described above, the eNB830, the base station apparatus850, or the module may be provided as an apparatus including the one or more components, and the program for causing the processor to function as the one or more components may be provided. A readable recording medium having recorded thereon the program may also be provided.

Further, in the eNB830illustrated inFIG. 23, the wireless communication unit120described with reference toFIG. 10may be implemented by the wireless communication interface825(for example, RF circuit827). Further, the antenna unit110may be implemented by the antenna810. Further, an interface between the processing unit240and an upper node or another base station apparatus may be implemented by the controller821and/or the network interface823.

Application Example of Terminal Apparatus

First Application Example

The processor901may be, for example, a CPU or a SoC (System on Chip), and controls functions of an application layer and another layer of the smartphone900. The memory902includes a RAM and a ROM, and stores a program that is executed by the processor901, and data. The storage903may include a storage medium such as a semiconductor memory or a hard disk. The external connection interface904is an interface for connecting an external device such as a memory card or a USB (Universal Serial Bus) device to the smartphone900.

The camera906includes an image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor), and generates a captured image. The sensor907may include a group of sensors such as a measurement sensor, a gyro sensor, a geomagnetic sensor, and an acceleration sensor. The microphone908converts sound that is input to the smartphone900to audio signals. The input device909includes, for example, a touch sensor configured to detect touch onto a screen of the display device910, a keypad, a keyboard, a button, or a switch, and receives an operation or information input from a user. The display device910includes a screen such as a liquid crystal display (LCD) or an organic light-emitting diode (OLED) display, and displays an output image of the smartphone900. The speaker911converts audio signals that are output from the smartphone900to sound.

The wireless communication interface912supports any cellular communication scheme such as LTE or LTE-Advanced, and executes wireless communication. The wireless communication interface912may typically include, for example, a BB processor913and an RF circuit914. The BB processor913may perform, for example, encoding/decoding, modulating/demodulating, and multiplexing/demultiplexing, to thereby execute various types of signal processing for wireless communication. Meanwhile, the RF circuit914may include, for example, a mixer, a filter, and an amplifier, and transmits and receives wireless signals via the antenna916. The wireless communication interface912may also be a single chip module having the BB processor913and the RF circuit914integrated thereon. The wireless communication interface912may include the plurality of BB processors913and the plurality of RF circuits914, as illustrated inFIG. 24. Note that, althoughFIG. 24illustrates the example in which the wireless communication interface912includes the plurality of BB processors913and the plurality of RF circuits914, the number of the BB processors913or RF circuits914of the wireless communication interface912may be one.

Furthermore, in addition to a cellular communication scheme, the wireless communication interface912may support other types of wireless communication schemes such as a short-distance wireless communication scheme, a near field communication scheme, and a wireless LAN (Local Area Network) scheme. In that case, the wireless communication interface912may include the BB processor913and the RF circuit914for each wireless communication scheme.

The antenna switches915each switch a connection destination of the corresponding antenna916among a plurality of circuits (for example, circuits for different wireless communication schemes) in the wireless communication interface912.

The antennas916each include one or a plurality of antenna elements (for example, a plurality of antenna elements of a MIMO antenna), and are used when wireless signals are transmitted or received via the wireless communication interface912. The smartphone900may include the plurality of antennas916, as illustrated inFIG. 24. Note that, althoughFIG. 24illustrates the example in which the smartphone900includes the plurality of antennas916, the smartphone900may include one antenna916.

In addition, the smartphone900may include the antenna916for each wireless communication scheme. In that case, the antenna switches915may be omitted from the configuration of the smartphone900.

The bus917connects the processor901, the memory902, the storage903, the external connection interface904, the camera906, the sensor907, the microphone908, the input device909, the display device910, the speaker911, the wireless communication interface912, and the auxiliary controller919to each other. The battery918supplies electric power to each block of the smartphone900illustrated inFIG. 24via feeder lines, which are partially illustrated as dashed lines inFIG. 24. The auxiliary controller919operates the minimum necessary function of the smartphone900in a sleep mode, for example.

In the smartphone900illustrated inFIG. 24, one or more components in the terminal apparatus200(for example, processing unit240), which are described with reference toFIG. 11, may be implemented by the wireless communication interface912. Alternatively, at least some of these components may be implemented by the processor901or the auxiliary controller919. As an example, the smartphone900may have mounted thereon a module including a part of the wireless communication interface912(for example, BB processor913) or all components thereof, the processor901, and/or the auxiliary controller919, and the one or more components may be implemented by the module in question. In this case, the module may store a program for causing the processor to function as the one or more components (in other words, a program for causing the processor to execute operations of the one or more components), to thereby execute the program in question. As another example, the smartphone900may have installed thereon the program for causing the processor to function as the one or more components, and the wireless communication interface912(for example, BB processor913), the processor901, and/or the auxiliary controller919may execute the program in question. As described above, the smartphone900or the module may be provided as an apparatus including the one or more components, and the program for causing the processor to function as the one or more components may be provided. A readable recording medium having recorded thereon the program may also be provided.

Further, in the smartphone900illustrated inFIG. 24, for example, the wireless communication unit220described with reference toFIG. 11may be implemented by the wireless communication interface912(for example, RF circuit914). Further, the antenna unit210may be implemented by the antenna916.

Second Application Example

FIG. 25is a block diagram illustrating an example of the schematic configuration of a car navigation apparatus920to which the technology according to the present disclosure may be applied. The car navigation apparatus920includes a processor921, a memory922, a GPS (Global Positioning System) module924, a sensor925, a data interface926, a content player927, a storage medium interface928, an input device929, a display device930, a speaker931, a wireless communication interface933, one or more antenna switches936, one or more antennas937, and a battery938.

The processor921may be, for example, a CPU or a SoC, and controls a navigation function and another function of the car navigation apparatus920. The memory922includes a RAM and a ROM, and stores a program that is executed by the processor921, and data.

The GPS module924uses GPS signals received from GPS satellites to measure a position (for example, latitude, longitude, and altitude) of the car navigation apparatus920. The sensor925may include a group of sensors such as a gyro sensor, a geomagnetic sensor, and a barometric sensor. The data interface926is connected to an in-vehicle network941via a terminal that is not illustrated, for example, and acquires data generated by a vehicle, such as vehicle speed data.

The content player927reproduces content stored in a storage medium (for example, CD or DVD) that is inserted into the storage medium interface928. The input device929includes, for example, a touch sensor configured to detect touch onto a screen of the display device930, a button, or a switch, and receives an operation or information input from a user. The display device930includes a screen such as an LCD or an OLED display, and displays an image of the navigation function or content that is reproduced. The speaker931outputs sound of the navigation function or the content that is reproduced.

The wireless communication interface933supports any cellular communication scheme such as LTE or LTE-Advanced, and executes wireless communication. The wireless communication interface933may typically include, for example, a BB processor934and an RF circuit935. The BB processor934may perform, for example, encoding/decoding, modulating/demodulating, and multiplexing/demultiplexing, to thereby execute various types of signal processing for wireless communication. Meanwhile, the RF circuit935may include, for example, a mixer, a filter, and an amplifier, and transmits and receives wireless signals via the antenna937. The wireless communication interface933may be a single chip module having the BB processor934and the RF circuit935integrated thereon. The wireless communication interface933may include the plurality of BB processors934and the plurality of RF circuits935, as illustrated inFIG. 25. Note that, althoughFIG. 25illustrates the example in which the wireless communication interface933includes the plurality of BB processors934and the plurality of RF circuits935, the number of the BB processors934or RF circuits935of the wireless communication interface933may be one.

Furthermore, in addition to a cellular communication scheme, the wireless communication interface933may support other types of wireless communication schemes such as a short-distance wireless communication scheme, a near field communication scheme, and a wireless LAN scheme. In that case, the wireless communication interface933may include the BB processor934and the RF circuit935for each wireless communication scheme.

The antenna switches936each switch a connection destination of the corresponding antenna937among plural circuits (for example, circuits for different wireless communication schemes) in the wireless communication interface933.

The antennas937each include one or a plurality of antenna elements (for example, a plurality of antenna elements of a MIMO antenna), and are used when wireless signals are transmitted or received via the wireless communication interface933. The car navigation apparatus920may include the plurality of antennas937, as illustrated inFIG. 25. Note that, althoughFIG. 25illustrates the example in which the car navigation apparatus920includes the plurality of antennas937, the car navigation apparatus920may include one antenna937.

In addition, the car navigation apparatus920may include the antenna937for each wireless communication scheme. In that case, the antenna switches936may be omitted from the configuration of the car navigation apparatus920.

The battery938supplies electric power to each block of the car navigation apparatus920illustrated inFIG. 25via feeder lines that are partially illustrated as dashed lines inFIG. 25. Further, the battery938accumulates electric power supplied from the vehicle.

In the car navigation apparatus920illustrated inFIG. 25, one or more components in the terminal apparatus200(for example, processing unit240), which are described with reference toFIG. 11, may be implemented by the wireless communication interface933. Alternatively, at least some of these components may be implemented by the processor921. As an example, the car navigation apparatus920may have mounted thereon a module including a part of the wireless communication interface933(for example, BB processor934) or all components thereof, and/or the processor921, and the one or more components may be implemented by the module in question. In this case, the module may store a program for causing the processor to function as the one or more components (in other words, a program for causing the processor to execute operations of the one or more components), to thereby execute the program in question. As another example, the car navigation apparatus920may have installed thereon the program for causing the processor to function as the one or more components, and the wireless communication interface933(for example, BB processor934) and/or the processor921may execute the program in question. As described above, the car navigation apparatus920or the module may be provided as an apparatus including the one or more components, and the program for causing the processor to function as the one or more components may be provided. A readable recording medium having recorded thereon the program may also be provided.

Further, in the car navigation apparatus920illustrated inFIG. 25, for example, the wireless communication unit220described with reference toFIG. 11may be implemented by the wireless communication interface912(for example, RF circuit914). Further, the antenna unit210may be implemented by the antenna916.

Further, the technology according to the present disclosure may also be realized as an in-vehicle system (or vehicle)940including the one or more blocks of the car navigation apparatus920, the in-vehicle network941, and a vehicle module942. The vehicle module942generates vehicle data such as vehicle speed, engine speed, or trouble information, and outputs the generated data to the in-vehicle network941.

Note that, the eNBs in the above description may each be a gNB (gNodeB or next generation Node B).

As described above, according to the embodiment of the present disclosure, there is provided the base station100or the terminal apparatus200that can reduce resources that are used in executing the beam sweeping process.

The respective steps of the processing that is executed by each apparatus described herein are not necessarily performed in chronological order in the order illustrated in the sequence diagrams or the flowcharts. For example, the respective steps of the processing that is executed by each apparatus may be performed in an order different from the order illustrated in the flowcharts or performed in parallel to each other.

Further, a computer program for causing hardware incorporated in each apparatus, such as a CPU, a ROM, and a RAM, to demonstrate the functions equivalent to the configurations of the apparatus can be created. Further, a storage medium having the computer program stored thereon can be provided. Further, with the respective functional blocks in the functional block diagrams achieved by hardware, a series of processes can be implemented by the hardware.

The preferred embodiment of the present disclosure is described in detail so far with reference to the attached drawings, but the technical scope of the present disclosure is not limited to the example. It is apparent that various changes or modifications could be arrived at by persons who have ordinary knowledge in the technical field to which the present disclosure belongs within the scope of the technical ideas described in the appended claims, and it is therefore understood that such changes or modifications naturally belong to the technical scope of the present disclosure.

Further, the effects described herein are merely illustrative or exemplary and are not limited. That is, the technology according to the present disclosure may provide other effects that are obvious for persons skilled in the art from the description of the present specification, in addition to the above-mentioned effects or instead of the above-mentioned effects.

Note that the following configurations also belong to the technical scope of the present disclosure.

(1) A communication apparatus including:

a control unit configured to change a setting of scan with a directional beam between beam groups each including a plurality of the directional beams,

in which the control unit adjusts the setting of the scan with the directional beam of each of the beam groups depending on a status of an area that the beam group covers.

(2) The communication apparatus according to Item (1), in which the control unit sets, as the setting, the number of the directional beams of the beam group.

(3) The communication apparatus according to Item (1) or (2), in which the control unit sets, as the setting, a period of the scan by the beam group.

(4) The communication apparatus according to any one of Items (1) to (3), in which the control unit sets, as the setting, output electric power from the directional beam of the beam group.

(5) The communication apparatus according to any one of Items (1) to (4), in which the control unit makes the communication apparatus transmit information associated with the beam group.

(6) The communication apparatus according to Item (5), in which the control unit makes the communication apparatus transmit information associated with a period of the scan as the information associated with the beam group.

(7) The communication apparatus according to Item (5) or (6), in which the control unit makes the communication apparatus transmit, as the information associated with the beam group, information regarding a beam group that a terminal apparatus configured to receive the directional beam is to observe.

(8) The communication apparatus according to Item (7), in which the control unit includes, in the information regarding a beam group to observe, information regarding a base station configured to output the directional beam.

(9) The communication apparatus according to Item (7) or (8), in which the control unit includes, in the information regarding a beam group to observe, information associated with a characteristic of the terminal apparatus.

(10) The communication apparatus according to Item (9), in which the control unit includes, in the information associated with the characteristic of the terminal apparatus, information associated with a movement state of the terminal apparatus.

(11) The communication apparatus according to any one of Items (5) to (10), in which the control unit makes the communication apparatus transmit, as the information associated with the beam group, information associated with evaluation of the beam group by a terminal apparatus configured to receive the directional beam.

(12) The communication apparatus according to any one of Items (5) to (11), in which the control unit makes the communication apparatus transmit the information associated with the beam group once per predetermined plural times of scan.

(13) The communication apparatus according to any one of Items (1) to (12), in which the beam group includes a plurality of directional beams in directions adjacent to each other.

(14) The communication apparatus according to any one of Items (1) to (13), in which the beam group includes the directional beams from a plurality of base stations.

(15) The communication apparatus according to any one of Items (1) to (14), in which the communication apparatus is included in a base station.

(16) The communication apparatus according to any one of Items (1) to (14), in which the communication apparatus is provided to a terminal configured to wirelessly communicate with the base station with the directional beam.

(17) A communication control method including:

changing, by a processor, a setting of scan with a directional beam between beam groups each including a plurality of the directional beams; and

adjusting, by the processor, the setting of the scan with the directional beam of each of the beam groups depending on a status of an area that the beam group covers.

(18) A computer program for causing a computer to execute:

changing a setting of scan with a directional beam between beam groups each including a plurality of the directional beams; and

adjusting the setting of the scan with the directional beam of each of the beam groups depending on a status of an area that the beam group covers.

REFERENCE SIGNS LIST