Patent Description:
In the Third Generation Partnership Project (3GPP), various techniques for improving the capacity of a cellular system are currently studied in order to accommodate explosively increasing traffic. It is also envisaged that the required capacity will become about <NUM> times the current capacity in the future. Techniques such as multi-user multi-input multiple-input multiple-output (MU-MIMO), coordinated multipoint (CoMP), and the like could increase the capacity of a cellular system by a factor of as low as less than ten. Therefore, there is a demand for an innovative technique.

For example, as a technique for significantly increasing the capacity of a cellular system, a base station may perform beamforming using a directional antenna including a large number of antenna elements (e.g., about <NUM> antenna elements). Such a technique is a kind of technique called large-scale MIMO or massive MIMO. By such beamforming, the half-width of a beam is narrowed. In other words, a sharp beam is formed. Also, if the large number of antenna elements are arranged in a plane, a beam aimed in a desired three-dimensional direction can be formed.

For example, Patent Literatures <NUM> to <NUM> disclose techniques applied when a directional beam aimed in a three-dimensional direction is used.

Patent Literature <NUM> discloses a method for beam coordination between a first base station and a second base station, wherein interfering beams transmitted from the first base station are determined based on measured interference signals, dependent on a ranking of interfering beams which shall be restricted in use. A restriction of use of radio resources in the first base station in at least one ranked interfering beam is performed, and user terminals served by the second base station are scheduled on radio resources which are restricted in use in the first base station is said at least one ranked interfering beam.

Patent Literature <NUM> discloses that random beams and FFR are used in combination, frequencies are grouped into a zone associated with the center of a cell and a zone associated with the border of the cell, and the random beams are applied only to the zone associated with the border of the cell. Since the number of resources to be allocated to the random beams decreases, a terminal lying on the border of the cell can reduce overhead. Using the zone associated with the center of the cell, beam scheduling can be freely performed within the cell.

Patent Literature <NUM> discloses a method of mitigating inter-cell interference, where terminals are grouped into groups. A base station transmits data to a first terminal belonging to a first group among the groups, without cooperation with a neighboring base station. The base station transmits data to a second terminal belonging to a second group among the groups, through cooperation with the neighboring base station.

Patent Literature <NUM> discloses examples for causing one or more subframes to be transmitted from a base station for a wireless network based on beamforming or transmission power characteristics. In some examples, an interference report may be received at a base station via a backhaul communication link. The interference report may indicate measured interference from the base station as measured at one or more wireless devices. The base station may transmit subsequent subframes in a manner to mitigate the previously reported interference. Other examples are described and claimed.

For example, when a base station performs beamforming, directional beams formed by the base station may reach a neighbor cell. Particularly, directional beams of large-scale MIMO may reach a neighbor cell and cause high received power. Consequently, large interference may be generated.

Accordingly, it is desirable to provide a system which enables interference of directional beams between cells to further decrease.

According to the present disclosure, there is provided a communication apparatus according to claim <NUM>.

In addition, according to the present disclosure, there is provided a corresponding method according to claim <NUM>.

In addition, according to the present disclosure, there is provided a non-transitory computer-readable medium including computer program instructions according to claim <NUM>.

As described above, according to the present disclosure, it is possible to further decrease interference of directional beams between cells.

In this specification and the appended drawings, structural elements that have substantially the same function and structure are denoted with the same reference numerals, and repeated explanation of these structural elements is omitted.

In addition, there are cases in the present specification and the diagrams in which constituent elements having substantially the same functional configuration are distinguished from each other by affixing different letters to the same reference numbers. For example, a plurality of constituent elements having substantially the same functional configuration are distinguished, like terminal apparatuses 200A, 200B, and 200C, if necessary. However, when there is no particular need to distinguish a plurality of constituent elements having substantially the same functional configuration from each other, only the same reference number is affixed thereto. For example, when there is no particular need to distinguish terminal apparatuses 200A, 200B, and 200C, they are referred to simply as terminal apparatuses <NUM>.

Description will be given in the following order.

First of all, techniques related to an embodiment of the present disclosure and consideration related to the present embodiment will be described with reference to <FIG>.

Beamforming and measurement will be described as techniques related to an embodiment of the present disclosure with reference to <FIG>.

In the 3GPP, various techniques for improving the capacity of a cellular system are currently studied in order to accommodate explosively increasing traffic. It is envisaged that the required capacity will become about <NUM> times the current capacity in the future. Techniques such as MU-MIMO, CoMP, and the like could increase the capacity of a cellular system by a factor of as low as less than ten. Therefore, there is a demand for an innovative technique.

Release <NUM> of the 3GPP specifies that eNode B is equipped with eight antennas. Therefore, the antennas can provide eight-layer MIMO in the case of single-user multi-input multiple-input multiple-output (SU-MIMO). Eight-layer MIMO is a technique of spatially multiplexing eight separate streams. Alternatively, the antennas can provide four-user two-layer MU-MIMO.

User equipment (UE) has only a small space for accommodating an antenna, and limited processing capability, and therefore, it is difficult to increase the number of antenna elements in the antenna of UE. However, recent advances in antenna mounting technology have allowed eNnode B to accommodate a directional antenna including about <NUM> antenna elements.

For example, as a technique for significantly increasing the capacity of a cellular system, a base station may perform beamforming using a directional antenna including a large number of antenna elements (e.g., about <NUM> antenna elements). Such a technique is a kind of technique called large-scale MIMO or massive MIMO. By such beamforming, the half-width of a beam is narrowed. In other words, a sharp beam is formed. Also, if the large number of antenna elements are arranged in a plane, a beam aimed in a desired three-dimensional direction can be formed. For example, it has been proposed that, by forming a beam aimed at a higher position than that of a base station (e.g., a higher floor of a high-rise building), a signal is transmitted to a terminal apparatus located at that position.

In typical beamforming, the direction of a beam can be changed in the horizontal direction. Therefore, it can be said that the typical beamforming is two-dimensional beamforming. Meanwhile, in large-scale MIMO (or massive MIMO) beamforming, the direction of a beam can be changed in the vertical direction as well as the horizontal direction. Therefore, it can be said that large-scale MIMO beamforming is three-dimensional beamforming.

Note that the increase in the number of antennas allows for an increase in the number of MU-MIMO users. Such a technique is another form of the technique called large-scale MIMO or massive MIMO. Note that when the number of antennas in UE is two, the number of spatially separated streams is two for a single piece of UE, and therefore, it is more reasonable to increase the number of MU-MIMO users than to increase the number of streams for a single piece of UE.

A set of weight for beamforming are represented by a complex number (i.e., a set of weight coefficients for a plurality of antenna elements). An example of a weight set particularly for large-scale MIMO beamforming will now be described with reference to <FIG>.

<FIG> is a diagram for describing a weight set for large-scale MIMO beamforming. <FIG> shows antenna elements arranged in a grid pattern. <FIG> also shows two orthogonal axes x and y in a plane in which the antenna elements are arranged, and an axis z perpendicular to the plane. Here, the direction of a beam to be formed is, for example, represented by an angle phi (Greek letter) and an angle theta (Greek letter). The angle phi (Greek letter) is an angle between an xy-plane component of the direction of a beam and the x-axis. Also, the angle theta (Greek letter) is an angle between the beam direction and the z-axis. In this case, for example, the weight coefficient Vm, n of an antenna element which is m-th in the x-axis direction and n-th in the y-axis direction is represented as follows.

In formula (<NUM>), f is a frequency, and c is the speed of light. Also, j is the imaginary unit of a complex number. Also, dx is an interval between each antenna element in the x-axis direction, and dy is an interval between each antenna element in the y-axis direction. Note that the coordinates of an antenna element are represented as follows.

A weight set for typical beamforming (two-dimensional beamforming) may be divided into a weight set for acquiring directivity in the horizontal direction and a weight set for phase adjustment of dual layer MIMO (i.e., a weight set for phase adjustment between two antenna subarrays corresponding to different polarized waves). On the other hand, a weight set for beamforming of large-scale MIMO (three-dimensional beamforming) may be divided into a first weight set for acquiring directivity in the horizontal direction, a second weight set for acquiring directivity in the vertical direction, and a third weight set for phase adjustment of dual layer MIMO.

When large-scale MIMO beamforming is performed, the gain reaches <NUM> dB or more. In a cellular system employing the above beamforming, a significant change in radio wave environment may occur compared to a conventional cellular system.

For example, a base station in urban areas may form a beam aimed at a high-rise building. Also, even in rural areas, a base station of a small cell may form a beam aimed at an area around the base station. Note that it is highly likely that a base station of a macro-cell in rural areas does not perform large-scale MIMO beamforming.

<FIG> is a diagram for describing an example of a case in which beamforming of large-scale MIMO is performed. Referring to <FIG>, a base station <NUM> and a high-rise building <NUM> are illustrated. For example, the base station <NUM> forms a directional beam <NUM> toward the high-rise building <NUM> in addition to directional beams <NUM> and <NUM> toward the ground.

Measurement includes measurement for selecting a cell and measurement for feeding back a channel quality indicator (CQI) and the like after connection. The latter is required to be performed in a shorter time. Measurement of an amount of interference from a neighbor cell as well as measurement of quality of a serving cell may be considered as a kind of such CQI measurement.

Although a cell-specific reference signal (CRS) may be used for CQI measurement, a channel state information reference signal (CSI-RS) has mainly been used for CQI measurement since release <NUM>.

A CSI-RS is transmitted without beamforming, similar to a CRS. That is, the CSI-RS is transmitted without being multiplied by a weight set for beamforming, similar to a CRS. A specific example of this will be described with reference to <FIG>.

<FIG> is a diagram for describing the relationship between multiplication of weight coefficients and insertion (or mapping) of a reference signal. Referring to <FIG>, a transmission signal <NUM> corresponding to each antenna element <NUM> is complex-multiplied by a weight coefficient <NUM> by a multiplier <NUM>. Thereafter, the transmission signal <NUM> complex-multiplied by the weight coefficient <NUM> is transmitted from the antenna element <NUM>. Also, a DR-MS <NUM> is inserted before the multiplier <NUM>, and is complex-multiplied by the weight coefficient <NUM> by the multiplier <NUM>. Thereafter, the DR-MS <NUM> complex-multiplied by the weight coefficient <NUM> is transmitted from the antenna element <NUM>. Meanwhile, a CRS <NUM> (and a CSI-RS) is inserted after the multiplier <NUM>. Thereafter, the CRS <NUM> (and the CSI-RS) is transmitted from the antenna element <NUM> without being multiplied by the weight coefficient <NUM>.

Since a CSI-RS is transmitted without beamforming as described above, a pure channel (or a channel response H) which is not affected by beamforming is estimated when measurement of the CSI-RS is performed. This channel H is used and a rank indicator (RI), a precoding matrix indicator (PMI) and a channel quality indicator (CQI) are fed back. Note that only a CQI is fed back depending on a transmission mode. Also, an amount of interference may be fed back.

Since a CSI-RS is transmitted without beamforming before release <NUM> as described above, the pure channel H which is not affected by beamforming is estimated when measurement of the CSI-RS is performed. Accordingly, the CSI-RS has been operated like a CRS.

A CRS is used for cell selection, synchronization and the like and thus a CRS transmission frequency is higher than a CSI-RS transmission frequency. That is, a CSI-RS period is longer than a CRS period.

There may be a first approach for transmitting a CSI-RS without beamforming and a second approach for transmitting a CSI-RS with beamforming (i.e., transmitting a CSI-RS over a directional beam) in a large-scale MIMO environment. It can be said that the first approach is a conventional approach and the second approach is a new approach. A relationship between multiplication by a weight coefficient and insertion of a reference signal in the new approach (second approach) will be described below with reference to <FIG>.

<FIG> is a diagram for describing relationship between multiplication by a weight coefficient and insertion (or mapping) of a reference signal in the new approach. Referring to <FIG>, a transmission signal <NUM> corresponding to each antenna element <NUM> is complex-multiplied by a weight coefficient <NUM> by a multiplier <NUM>. Thereafter, the transmission signal <NUM> complex-multiplied by the weight coefficient <NUM> is transmitted from the antenna element <NUM>. Also, a DR-MS <NUM> is inserted before the multiplier <NUM>, and is complex-multiplied by the weight coefficient <NUM> by the multiplier <NUM>. Thereafter, the DR-MS <NUM> complex-multiplied by the weight coefficient <NUM> is transmitted from the antenna element <NUM>. Further, a CSI-RS <NUM> is inserted in front of the multiplier <NUM>, and is complex-multiplied by the weight coefficient <NUM> in the multiplier <NUM>. Then, the CSI-RS <NUM> complex-multiplied by the weight coefficient <NUM> is transmitted from the antenna element <NUM>. Meanwhile, a CRS <NUM> (and a normal CSI-RS) is inserted after the multiplier <NUM>. Thereafter, the CRS <NUM> (and the normal CSI-RS) is transmitted from the antenna element <NUM> without being multiplied by the weight coefficient <NUM>.

Consideration related to an embodiment of the present disclosure will be described with reference to <FIG>.

In an environment in which directional beams formed by an eNB are not reflected, interference is not generated between directional beams formed by the eNB. On the other hand, in an environment in which directional beams formed by an eNB are reflected, interference may be generated between directional beams formed by the eNB. A specific example of this will be described below with reference to <FIG> and <FIG>.

<FIG> is a diagram for describing an example of an environment in which directional beams are not reflected. Referring to <FIG>, an eNB <NUM> and UEs <NUM>, <NUM> and <NUM> are illustrated. For example, the eNB <NUM> forms a directional beam <NUM> directed toward the UE <NUM>, a directional beam <NUM> directed toward the UE <NUM> and a directional beam <NUM> directed toward the UE <NUM>. In this example, the directional beams <NUM>, <NUM> and <NUM> are not reflected and interference is not generated among the directional beams <NUM>, <NUM> and <NUM>.

<FIG> is a diagram for describing an example of an environment in which directional beams are reflected. Referring to <FIG>, an eNB <NUM> and UEs <NUM>, <NUM> and <NUM> are shown. Further, obstacles <NUM> and <NUM> are shown. For example, the obstacles <NUM> and <NUM> are buildings. For example, the eNB <NUM> forms a directional beam <NUM> directed toward the UE <NUM>, a directional beam <NUM> directed toward the UE <NUM> and directional beams <NUM> directed toward the UE <NUM>. In this example, the directional beams <NUM> are reflected by the obstacles <NUM> and <NUM> and arrive at the UE <NUM>. Accordingly, interference is generated between the directional beam <NUM> and the directional beams <NUM>.

Not only interference between directional beams in a cell but also interference between directional beams of different cells may be generated. A specific example of this will be described below with reference to <FIG>.

<FIG> is a diagram for describing an example of interference between directional beams of different cells. Referring to <FIG>, eNBs <NUM> and <NUM> and UEs <NUM>, <NUM> and <NUM> are shown. For example, the eNB <NUM> forms a directional beam <NUM> toward the UE <NUM>, a directional beam <NUM> toward the UE <NUM> and a directional beam <NUM> toward the UE <NUM>. In addition, the eNB <NUM> forms a directional beam <NUM> which arrives at the UE <NUM>. Accordingly, interference is generated between the directional beam <NUM> formed by the eNB <NUM> and the directional beam <NUM> formed by the eNB <NUM>.

As described above, when interference of a directional beam in a cell and/or interference of a directional beam between cells are generated, received quality of a UE deteriorates, and thus system throughput may decrease.

Interference may be generated between two directional beams or interference may be generated among three or more directional beams. How many directional beams generate interference varies according to UEs. Referring to <FIG>, for example, interference is not generated in the UEs <NUM> and <NUM>, whereas interference is generated among three directional beams in the UE <NUM>. That is, an interference situation varies depending on place.

It can be said that a single operating band includes a high frequency band (component carriers) and a low frequency band (component carriers) but interference situations in the frequency bands are nearly the same.

When only a desired directional beam arrives at a UE, the UE can obtain high received quality. On the other hand, when not only a desired directional beam but also other directional beams arrive at a UE, received quality of the UE may deteriorate.

In order to suppress such interference, first of all, it is important for an eNB to ascertain a situation of interference of a directional beam. A UE reporting a situation of interference of a directional beam to the eNB is considered because the eNB cannot be aware of the situation of such interference of the directional beam. For example, calculating an amount of interference of a directional beam other than a desired directional beam from a CSI-RS is considered. Also, use of a CSI feedback procedure is considered.

In general, there are two types of channel quality measurement. One type is radio resource management (RRM) measurement such as measurement of reference signal received power (RSRP) and reference signal received quality (RSRQ) and the other is measurement for deciding an RI, a CQI, a PMI and the like included in CSI. The former is mainly performed for cell selection by both a UE in an RRC idle mode and a UE in an RRC connected mode. On the other hand, the latter is performed to recognize an interference situation by a UE in an RRC connected mode.

A CSI-RS is defined in release <NUM>. A normal CSI-RS is also referred to as a non-zero-power CSI-RS. The purpose of the CSI-RS is to acquire a pure channel and thus the CSI-RS is transmitted without beamforming.

Also, a zero-power CSI-RS is defined. The zero-power CSI-RS is defined in order to enable easy observation of relatively weak signals from other eNBs. Since an eNB does not transmit a signal in radio resources (resource elements) for the zero-power CSI-RS, a UE can receive signals from other eNBs in the radio resources.

A CSI-RS period is variable between <NUM> and <NUM>. In addition, <NUM> radio resources are prepared in one subframe as candidates for radio resources in which the CSI-RS is transmitted.

Conventionally, only one CSI-RS is configured for one cell. On the other hand, a plurality of zero-power CSI-RSs can be configured for one cell. Accordingly, when a serving eNB of a UE configures a zero-power CSI-RS in accordance with a configuration of a CSI-RS of a neighbor eNB, the UE can perform measurement of the CSI-RS of the neighbor eNB without being affected by a signal from the serving eNB.

Note that a CSI-RS configuration is cell-specific. A UE may be notified of the configuration through signaling of a higher layer.

Next, a schematic configuration of a communication system <NUM> according to an embodiment of the present disclosure will be described with reference to <FIG> is a diagram for describing an example of the schematic configuration of the communication system <NUM> according to an embodiment of the present disclosure. Referring to <FIG>, the system <NUM> includes a base station <NUM>, a terminal apparatus <NUM>, and a base station <NUM>. The system <NUM> is a system which complies with, for example, LTE, LTE-Advanced, or similar communication standards.

The base station <NUM> performs wireless communication with the terminal apparatuses <NUM>. For example, the base station <NUM> performs wireless communication with the terminal apparatuses <NUM> located in a cell <NUM> of the base station <NUM>.

Particularly, in an embodiment of the present disclosure, the base station <NUM> performs beamforming. For example, the beamforming is beamforming of large-scale MIMO. The beamforming may also be referred to as beamforming of massive MIMO, beamforming of free dimension MIMO or three-dimensional beamforming. Specifically, for example, the base station <NUM> includes a directional antenna usable for large-scale MIMO and performs beamforming of large-scale MIMO by multiplying a transmission signal by a weight set for the directional antenna.

For example, the base station <NUM> transmits a reference signal for channel quality measurement over a directional beam. For example, the reference signal is a CSI-RS. Note that the embodiment of the present disclosure is not limited to such an example and the base station <NUM> may transmit the reference signal without beamforming.

The terminal apparatus <NUM> performs wireless communication with a base station. For example, the terminal apparatus <NUM> performs wireless communication with the base station <NUM> when located within a cell <NUM> of the base station <NUM>. For example, the base station <NUM> performs wireless communication with a base station <NUM> when located within a cell <NUM> of the base station <NUM>.

For example, terminal apparatuses 200A, 200B, 200C and 200D are connected to the base station <NUM>. That is, the base station <NUM> is a serving base station of the terminal apparatuses 200A, 200B, 200C and 200D and the cell <NUM> is a serving cell of the terminal apparatuses 200A, 200B, 200C and 200D.

For example, terminal apparatuses 200E, 200F, <NUM> and <NUM> are connected to the base station <NUM>. That is, the base station <NUM> is a serving base station of the terminal apparatuses 200E, 200F, <NUM> and <NUM> and the cell <NUM> is a serving cell of the terminal apparatuses 200E, 200F, <NUM> and <NUM>.

The base station <NUM> is a neighbor base station of the base station <NUM>. It may also be said that the base station <NUM> is a neighbor base station of the base station <NUM>.

For example, the base station <NUM> has the same configuration as the base station <NUM> and performs the same operation as the base station <NUM>. In other words, the base station <NUM> has the same configuration as the base station <NUM> and performs the same operation as the base station <NUM>.

Although <FIG> illustrates only the base station <NUM> as a neighbor base station of the base station <NUM>, of course, the system <NUM> may include a plurality of neighbor base stations of the base station <NUM>.

Note that both the base station <NUM> and the base station <NUM> may be base stations of macro cells. Alternatively, both the base station <NUM> and the base station <NUM> may be base stations of small cells. Alternatively, one of the base station <NUM> and the base station <NUM> may be a base station of a macro cell and the other of the base station <NUM> and the base station <NUM> may be a base station of a small cell.

Next, examples of configurations of the base station <NUM> and the terminal apparatus <NUM> will be described with reference to <FIG> and <FIG>.

First of all, an example of the configuration of the base station <NUM> according to an embodiment of the present disclosure will be described with reference to <FIG> is a block diagram showing an example of the configuration of the base station <NUM> according to the embodiment of the present disclosure. Referring to <FIG>, the base station <NUM> includes an antenna unit <NUM>, a wireless communication unit <NUM>, a network communication unit <NUM>, a storage unit <NUM>, and a processing unit <NUM>.

The antenna unit <NUM> radiates a signal output by the wireless communication unit <NUM>, in the form of radio waves, into space. The antenna unit <NUM> also converts radio waves in space into a signal, and outputs the signal to the wireless communication unit <NUM>.

For example, the antenna unit <NUM> includes a directional antenna. For example, the directional antenna is a directional antenna which can be used in large-scale MIMO.

The wireless communication unit <NUM> transmits and receives signals. For example, the wireless communication unit <NUM> transmits a downlink signal to the terminal apparatus <NUM> and receives an uplink signal from the terminal apparatus <NUM>.

The network communication unit <NUM> transmits and receives information. For example, the network communication unit <NUM> transmits information to other nodes and receives information from other nodes. For example, the other nodes include other base stations (for example, base station <NUM>) and a core network node.

The storage unit <NUM> stores programs and data for operation of the base station <NUM>.

The processing unit <NUM> provides various functions of the base station <NUM>. The processing unit <NUM> includes an information acquisition unit <NUM> and a control unit <NUM>. Note that the processing unit <NUM> may further include other components in addition to such components. That is, the processing unit <NUM> may perform operations other than operations of such components.

Specific operations of the information acquisition unit <NUM> and the control unit <NUM> will be described below in detail.

Next, an example of the configuration of the terminal apparatus <NUM> according to an embodiment of the present disclosure will be described with reference to <FIG> is a block diagram for showing an example of the configuration of the terminal apparatus <NUM> according to the embodiment of the present disclosure. Referring to <FIG>, the terminal apparatus <NUM> includes an antenna unit <NUM>, a wireless communication unit <NUM>, a storage unit <NUM> and a processing unit <NUM>.

The wireless communication unit <NUM> transmits and receives signals. For example, the wireless communication unit <NUM> receives a downlink signal from the base station and transmits an uplink signal to the base station.

The storage unit <NUM> stores a program and data for operation of the terminal apparatus <NUM>.

The processing unit <NUM> provides various functions of the terminal apparatus <NUM>. The processing unit <NUM> includes an interference amount calculation unit <NUM>, a detection unit <NUM> and a reporting unit <NUM>. Note that the processing unit <NUM> may further include components other than such components. That is, the processing unit <NUM> may also perform operations other than operations of such components.

Specific operations of the interference amount calculation unit <NUM>, the detection unit <NUM> and the reporting unit <NUM> will be described below in detail.

Next, technical features according to the embodiment of the present disclosure will be described.

For example, the terminal apparatus <NUM> (interference amount calculation unit <NUM>) connected to the base station <NUM> calculates an amount of interference of a directional beam from a reference signal for channel quality measurement (e.g., a CSI-RS) transmitted by the base station <NUM>.

As an example, the base station <NUM> transmits a reference signal for channel quality measurement over each of a plurality of directional beams which can be formed by the base station <NUM>. In this case, the terminal apparatus <NUM> calculates an amount of interference of each of the plurality of directional beams from the reference signal for channel quality measurement transmitted over each of the plurality of directional beams. Note that, for example, a configuration (e.g., a radio resource used for transmission and/or a signal of) of a reference signal for channel quality measurement is different for each directional beam. Accordingly, it is possible to calculate an amount of interference of each directional beam.

As another example, the base station <NUM> may transmit a reference signal for channel quality measurement without beamforming. In this case, the terminal apparatus <NUM> may estimate a channel from the reference signal and virtually calculate an amount of interference of each of the plurality of directional beams on the basis of the channel and a plurality of precoding matrices corresponding to the plurality of directional beams. Specifically, the terminal apparatus <NUM> may calculate an amount of interference I(i) of a directional beam i = H*PM(i) on the basis of a channel H and a precoding matrix PM(i) of the directional beam i.

Note that, instead of the terminal apparatus <NUM>, the base station <NUM> may virtually calculate an amount of interference of each of the plurality of directional beams on the basis of a channel reported by the terminal apparatus <NUM> (reporting unit <NUM>) and the plurality of precoding matrices.

In the embodiment of the present disclosure, the base station <NUM> (i.e., a neighbor base station of the base station <NUM>) provides, to the base station <NUM>, information about a directional beam which is an interference source for the terminal apparatus <NUM> connected to the base station <NUM> (referred to as "interference beam information" hereinafter) from among a plurality of directional beams which can be formed by the base station <NUM>.

For example, the directional beam which is an interference source for the terminal apparatus <NUM> is a directional beam having a large amount of interference (e.g., a directional beam having an amount of interference exceeding a threshold value) in the terminal apparatus <NUM>. In this case, when there is a directional beam having a large amount of interference (e.g., a directional beam having an amount of interference exceeding a threshold value) in the terminal apparatus <NUM> connected to the base station <NUM>, the base station <NUM> provides information about the directional beam (i.e., interference beam information) to the base station <NUM>.

More specifically, on the basis of an amount of interference of a directional beam reported by the terminal apparatus <NUM> (reporting unit <NUM>), for example, the base station <NUM> determines whether the amount of interference of the directional beam is large (e.g., whether the amount of interference exceeds a threshold value). Thereafter, the base station <NUM> provides information about the directional beam (i.e., interference beam information) to the base station <NUM> when it is determined that the amount of interference of the directional beam is large (e.g., the amount of interference exceeds the threshold value).

Alternatively, the terminal apparatus <NUM> may determine whether the amount of interference of the directional beam is large (e.g., whether the amount of interference exceeds the threshold value). Thereafter, the terminal apparatus <NUM> (reporting unit <NUM>) may report the directional beam to the base station <NUM> when it is determined that the amount of interference of the directional beam is large (e.g., the amount of interference exceeds the threshold value). Then, the base station <NUM> may provide the information about the directional beam (i.e., interference beam information) to the base station <NUM>.

The directional beam which is an interference source for the terminal apparatus <NUM> may be a directional beam from which an amount of interference in the terminal apparatus <NUM> is calculated. In this case, the base station <NUM> may provide information about the directional beam from which the amount of interference in the terminal apparatus <NUM> is calculated (i.e., interference beam information) to the base station <NUM> irrespective of whether the amount of interference is large or small. In this case, the base station <NUM> may determine whether the amount of interference of the directional beam is large (e.g., whether the amount of interference exceeds the threshold value).

The directional beam which is an interference source for the terminal apparatus <NUM> may be a directional beam which obstructs detection of another reference signal for channel quality measurement in the terminal apparatus <NUM>. The other reference signal may be a reference signal transmitted by another base station in the same radio resource as that for the reference signal transmitted by the base station <NUM>. In this case, when there is a directional beam which obstructs the other reference signal for channel quality measurement, the base station <NUM> may provide information about the directional beam (i.e., interference beam information) to the base station <NUM>.

For example, the interference beam information includes information for specifying the directional beam (referred to as "specification information" hereinafter).

As an example, the specification information is information which indicates a precoding matrix (e.g., a PMI) used to form the directional beam.

As another example, a reference signal for channel quality measurement (e.g., a CSI-RS) may be transmitted over a directional beam and a configuration of a reference signal for channel quality measurement may be provided to each directional beam. That is, a directional beam and a configuration may be correlated. In this case, the specification information may be information indicating a configuration of a reference signal for channel quality measurement.

Accordingly, the base station <NUM> may recognize a directional beam to handle, for example.

The interference beam information may include information indicating the amount of interference of the directional beam. The amount of interference may be the amount of interference of the directional beam in the terminal apparatus <NUM> connected to the base station <NUM>. Accordingly, the base station <NUM> may execute an operation depending on the amount of interference, for example.

For example, the base station <NUM> generates a message (a message for the base station <NUM>) including the interference beam information. Thereafter, the base station <NUM> transmits the message to the base station <NUM>.

In the embodiment of the present disclosure, the base station <NUM> (information acquisition unit <NUM>) acquires the interference beam information (i.e., information about a directional beam which is an interference source for the terminal apparatus <NUM> connected to the base station <NUM> from among a plurality of directional beams which can be formed by the base station <NUM>) provided by the base station <NUM>. Thereafter, the base station <NUM> (control unit <NUM>) decides an operation of the base station <NUM> regarding transmission of a signal over the directional beam on the basis of the interference beam information.

For example, the signal includes a data signal.

For example, the signal includes a reference signal for channel quality measurement. More specifically, the reference signal is a channel state information reference signal (CSI-RS), for example.

As a first example, the base station <NUM> (control unit <NUM>) decides suspension of transmission of the signal over the directional beam as the operation. Thereafter, the base station <NUM> suspends transmission of the signal over the directional beam.

For example, the base station <NUM> (control unit <NUM>) decides and executes suspension of transmission of a data signal and/or the reference signal over the directional beam.

Accordingly, it is possible to cancel interference of the directional beam in the terminal apparatus <NUM> connected to the base station <NUM>, for example.

As a second example, the base station <NUM> (control unit <NUM>) decides restriction on transmission of the signal over the directional beam as the operation. Thereafter, the base station <NUM> restricts transmission of the signal over the directional beam.

For example, the restriction includes restricting radio resources in which a data signal is transmitted over the directional beam. That is, the base station <NUM> (control unit <NUM>) decides restriction on radio resources in which a data signal is transmitted over the directional beam and restricts the radio resources. Consequently, the base station <NUM> transmits the data signal in the restricted radio resources over the directional beam.

More specifically, the restriction includes restricting, for example, time resources in which a data signal is transmitted over the directional beam. For example, the time resources are subframes. In this case, the base station <NUM> transmits the data signal in the restricted subframes over the directional beam.

Note that the restriction may include restricting frequency resources in which a data signal is transmitted over the directional beam. Also, the restriction may include restricting time and frequency resources in which a data signal is transmitted over the directional beam.

For example, the restriction includes lengthening a period of transmission of a reference signal for channel quality measurement. That is, the base station <NUM> (control unit <NUM>) decides lengthening of a period of transmission of a reference signal for channel quality measurement over the directional beam and lengthens the period. That is, the base station <NUM> (control unit <NUM>) changes the period in the configuration of the reference signal for channel quality measurement transmitted over the direction beam to a long period.

Accordingly, it is possible to suppress interference of the directional beam in the terminal apparatus <NUM> connected to the base station <NUM>, for example.

For example, the base station <NUM> (control unit <NUM>) decides continuation of transmission of the signal over the directional beam as the operation. Thereafter, the base station <NUM> continuously transmits the signal over the directional beam.

Accordingly, it is possible to continue transmission of the signal over the directional beam when it is difficult to suspend and restrict transmission of the signal over the directional beam, for example.

The restriction may include changing the configuration (e.g., radio resources used to transmit a signal (including a period) and/or a sequence of the signal) of a reference signal for channel quality measurement through the directional beam. That is, the base station <NUM> (control unit <NUM>) may decide changing of the configuration and change the configuration.

As described above, the directional beam may be a directional beam which obstructs detection of another reference signal for channel quality measurement (e.g., another CSI-RS) in the terminal apparatus <NUM>. The base station <NUM> (control unit <NUM>) may decide changing of the configuration and change the configuration.

Accordingly, the terminal apparatus <NUM> connected to the base station <NUM> can detect another reference signal for channel quality measurement, for example.

For example, the base station <NUM> (control unit <NUM>) decides an operation of the base station <NUM> from among the aforementioned various operations. Hereinafter, examples of a technique for deciding the operation will be described. Note that decision of the operation according to the present embodiment is not limited to such examples.

For example, the base station <NUM> may transmit a data signal to neither of terminal apparatuses <NUM> over the directional beam. In this case, the base station <NUM> (control unit <NUM>) decides and executes suspension of transmission of the data signal over the directional beam, for example.

For example, the base station <NUM> transmits a data signal to a small number of terminal apparatuses <NUM> (e.g., a number of terminal apparatuses <NUM> equal to or less than a predetermined number) over the directional beam. In this case, for example, the base station <NUM> (control unit <NUM>) decides and executes restriction on transmission of the data signal over the directional beam (e.g., restriction on radio resources in which the data signal is transmitted over the directional beam).

For example, the base station <NUM> transmits a data signal to a large number of terminal apparatuses <NUM> (e.g., a number of terminal apparatuses <NUM> exceeding a predetermined number) over the directional beam. In this case, for example, the base station <NUM> (control unit <NUM>) decides and executes continuation of transmission of the data signal over the directional beam.

For example, the number of terminal apparatuses <NUM> connected to the base station <NUM> and located in a radiation direction of the directional beam is small. More specifically, the number of terminal apparatuses <NUM> located in the radiation direction of the directional beam is equal to or less than a predetermined number, for example. In this case, the base station <NUM> (control unit <NUM>) decides and executes suspension of or restriction on transmission of a data signal and/or a reference signal for channel quality measurement over the directional beam.

For example, the number of terminal apparatuses <NUM> connected to the base station <NUM> and located in the radiation direction of the directional beam is large. More specifically, the number of terminal apparatuses <NUM> located in the radiation direction of the directional beam exceeds the predetermined number, for example. In this case, the base station <NUM> (control unit <NUM>) decides and executes continuation of transmission of a data signal and/or a reference signal for channel quality measurement over the directional beam.

Note that the predetermined number may be equal to or larger than <NUM> or may be <NUM>.

As described above, the base station <NUM> (control unit <NUM>) decides an operation of the base station <NUM> regarding transmission of the signal over the directional beam on the basis of the interference beam information. Accordingly, it is possible to further decrease interference of a directional beam between cells (i.e., between the cell <NUM> and the cell <NUM>), for example.

For example, the base station <NUM> (control unit <NUM>) notifies the base station <NUM> of the operation of the base station <NUM> regarding transmission of the signal over the directional beam.

More specifically, for example, the base station <NUM> (control unit <NUM>) generates a message (a message for the base station <NUM>) including operation information indicating the operation (e.g., suspension, restriction or continuation) of the base station <NUM> regarding transmission of the signal over the directional beam. Thereafter, the base station <NUM> transmits the message to the base station <NUM> through an interface (e.g., an X2 interface) between the base station <NUM> and the base station <NUM>.

Accordingly, the base station <NUM> can recognize how interference of a directional beam in the terminal apparatus <NUM> connected to the base station <NUM> changes, for example.

The base station <NUM> (control unit <NUM>) may notify the base station <NUM> of the operation of the base station <NUM> regarding transmission of the signal over the directional beam.

The base station <NUM> (control unit <NUM>) may decide and execute, as the operation, change of a configuration of a reference signal for channel quality measurement transmitted over the directional beam (including lengthening the period). In this case, the base station <NUM> may notify the terminal apparatus <NUM> of the change of the configuration.

For example, the base station <NUM> (control unit <NUM>) cancels the operation of the base station <NUM> regarding transmission of the signal over the directional beam when a cancellation condition is satisfied. For example, the operation is suspension, restriction, or the like of transmission of the signal over the directional beam. Accordingly, it is possible to set suspension of or restriction on transmission of the signal over the directional beam within a limited range, for example.

For example, the cancellation condition includes a condition that an elapsed time from initiation of the operation exceed a predetermined time. That is, the base station <NUM> (control unit <NUM>) cancels the operation when the elapsed time from initiation of the operation exceeds the predetermined time.

More specifically, the base station <NUM> (control unit <NUM>) starts a timer when the operation of the base station <NUM> regarding transmission of the signal over the directional beam is initiated, for example. Thereafter, the base station <NUM> (control unit <NUM>) cancels the operation when the timer expires.

Accordingly, it is possible to set suspension of or restriction on transmission of the signal over the directional beam within a limited time, for example.

For example, the cancellation condition includes reception, by the base station <NUM>, of cancellation information about cancellation of the operation from the base station <NUM>. That is, the base station <NUM> (control unit <NUM>) cancels the operation upon receiving the cancellation information from the base station <NUM>.

For example, the base station <NUM> generates a cancellation message including the cancellation information and transmits the cancellation message to the base station <NUM>.

For example, the cancellation information includes information for specifying the directional beam (i.e., specification information).

The cancellation information may include restriction information indicating restriction on transmission of the signal over the directional beam after cancellation.

Specifically, the restriction information may indicate, as the restriction, radio resources or a period in which the signal is transmitted over the directional beam. Also, the restriction information may indicate a configuration of a reference signal for channel quality measurement transmitted over the directional beam as the restriction.

In such a case, the base station <NUM> may transmit the signal over the directional beam in accordance with the restriction indicated by the restriction information after cancellation of the operation.

According to such restriction information, it is possible to adjust a balance between transmission of a directional beam and avoidance or suppression of interference more flexibly, for example.

For example, the base station <NUM> transmits the cancellation information to the base station <NUM> when interference of the directional beam is assumed to be small.

As a first example, the base station <NUM> transmits the cancellation information to the base station <NUM> when the terminal apparatus <NUM> (terminal apparatus <NUM> connected to the base station <NUM>) which receives interference of the directional beam finishes receiving a data signal.

As a second example, the base station <NUM> transmits the cancellation information to the base station <NUM> when the terminal apparatus <NUM> (terminal apparatus <NUM> connected to the base station <NUM>) which receives interference of the directional beam at a certain position moves from the certain position to a different position.

As a third example, the terminal apparatus <NUM> connected to the base station <NUM> may detect a radio resource having a small amount of interference from among radio resources in which reference signals for channel quality measurement are transmitted. In this case, the base station <NUM> may transmit cancellation information related to suspension of or restriction on a reference signal for channel quality measurement to the base station <NUM>. The cancellation information may include information indicating a configuration including the radio resource as restriction information indicating restriction on transmission of a reference signal for channel quality measurement over the directional beam after cancellation. Thereafter, the base station <NUM> may transmit a reference signal for channel quality measurement having the configuration over the directional beam.

Note that the terminal apparatus <NUM> (interference amount calculation unit <NUM>) may calculate an amount of interference from a reference signal for channel quality measurement transmitted by a neighbor base station (including a neighbor base station other than the base station <NUM>) of the base station <NUM> that is a serving base station. Thereafter, the terminal apparatus <NUM> (detection unit <NUM>) may detect a radio resource having a small amount of interference (e.g., a radio resource having an amount of interference less than a threshold value) from among radio resources in which the reference signal is transmitted. Then, the terminal apparatus <NUM> (reporting unit <NUM>) may report the radio resource having a small amount of interference to the base station <NUM>. Thereafter, the base station <NUM> may transmit cancellation information to the base station <NUM>, and the cancellation information may include information indicating a configuration including the radio resource as restriction information.

A trigger of transmission of the cancellation information to the base station <NUM> is not limited to the aforementioned first to third examples and may be a different one.

For example, the base station <NUM> (control unit <NUM>) notifies the base station of completion of cancellation of the operation. For example, the base station <NUM> (control unit <NUM>) transmits a message including cancellation completion information indicating completion of cancellation of the operation to the base station <NUM>.

Note that the base station <NUM> (control unit <NUM>) may notify the terminal apparatus <NUM> of completion of cancellation of the operation.

Next, an example of a process according to the embodiment of the present disclosure will be described with reference to <FIG>.

<FIG> is a sequence diagram illustrating a first example of a schematic flow of the process according to the embodiment of the present disclosure.

The base station <NUM> transmits a reference signal for channel quality measurement (e.g., a CSI-RS) (S401).

The terminal apparatus <NUM> connected to the base station <NUM> calculates an amount of interference from the reference signal (S403). For example, the terminal apparatus <NUM> calculates an amount of interference of each of a plurality of directional beams which can be formed by the base station <NUM>.

Further, the terminal apparatus <NUM> reports the amount of interference to the base station <NUM> (S405). For example, the terminal apparatus <NUM> transmits an interference report indicating the amount of interference to the base station <NUM>.

The base station <NUM> provides, to the base station <NUM>, information (i.e., interference beam information) about a directional beam which is an interference source for the terminal apparatus <NUM> connected to the base station <NUM> (e.g., a directional beam having a large amount of interference in the terminal apparatus <NUM>) from among the plurality of directional beams (S407). For example, the base station <NUM> transmits a message including the interference beam information to the base station <NUM>.

The base station <NUM> acquires the interference beam information and decides an operation of the base station <NUM> regarding transmission of a signal over the directional beam on the basis of the interference beam information (S409). Then, the base station <NUM> executes the operation (S411). Also, the base station <NUM> notifies the base station <NUM> of the operation (S413). For example, the base station <NUM> transmits a message including operation information indicating the operation to the base station <NUM>.

Note that the base station <NUM> may notify the terminal apparatus <NUM> connected to the base station <NUM> of the operation. Also, the base station <NUM> may notify the terminal apparatus <NUM> connected to the base station <NUM> of the operation.

<FIG> is a sequence diagram illustrating a second example of a schematic flow of the process according to the embodiment of the present disclosure.

Here, description of steps S431 to S441 and S445 in the second example illustrated in <FIG> is the same as description of steps S401 to S413 in the first example illustrated in <FIG>, and thus only steps S443 and S447 to S451 will be described.

The base station <NUM> starts a timer when an operation regarding transmission of a signal over a directional beam (i.e., the operation decided in step S431) is initiated (S443).

Thereafter, the base station <NUM> cancels the operation (S449) when the timer expires (S447). Then, the base station <NUM> notifies the base station <NUM> of completion of cancellation of the operation (S451). For example, the base station <NUM> transmits a message including cancellation completion information indicating completion of cancellation of the operation to the base station <NUM>.

Note that the base station <NUM> may notify the terminal apparatus <NUM> connected to the base station <NUM> of completion of cancellation of the operation. Also, the base station <NUM> may notify the terminal apparatus <NUM> connected to the base station <NUM> of completion of cancellation of the operation.

<FIG> is a sequence diagram illustrating a third example of a schematic flow of the process according to the embodiment of the present disclosure.

Here, description of steps S461 to S473 in the third example illustrated in <FIG> is the same as description of steps S401 to S413 in the first example illustrated in <FIG>, and thus only steps S475 to S479 will be described.

The base station <NUM> transmits cancellation information about cancellation of an operation regarding transmission of a signal over a directional beam (i.e., the operation decided in step S469) to the base station <NUM> (S475). For example, the base station <NUM> transmits a message including the cancellation information to the base station <NUM>.

The base station <NUM> cancels the operation in response to reception of the cancellation information (S477). Then, the base station <NUM> notifies the base station <NUM> of completion of cancellation of the operation (S479). For example, the base station <NUM> transmits a message including cancellation completion information indicating completion of cancellation of the operation to the base station <NUM>.

The technique according to the present disclosure is applicable to various products. The base station <NUM> may also be implemented, for example, as any type of evolved Node B (eNB) such as macro eNBs and small eNBs. Small eNBs may cover smaller cells than the macrocells of pico eNBs, micro eNBs, or home (femt) eNBs. Instead, the base station <NUM> may be implemented as another type of base station such as Nodes B or base transceiver stations (BTSs). The base station <NUM> may include the main apparatus (which is also referred to as base station apparatus) that controls wireless communication and one or more remote radio heads (RRHs) that are disposed at different locations from that of the main apparatus. Also, various types of terminals described below may function as the base station <NUM> by temporarily or semi-permanently executing the functionality of the base station. Furthermore, at least some of components of the base station <NUM> may be realized in a base station apparatus or a module for a base station apparatus.

Further, the terminal apparatus <NUM> may be implemented as a mobile terminal such as smartphones, tablet personal computers (PCs), notebook PCs, portable game terminals, portable/dongle mobile routers, and digital cameras, or an in-vehicle terminal such as car navigation apparatuses. The terminal apparatus <NUM> may be implemented as a machine type communication (MTC) for establishing a machine to machine communication (M2M). Furthermore, at least some of components of the terminal apparatus <NUM> may be implemented as a module (e.g. integrated circuit module constituted with a single die) that is mounted on these terminals.

<FIG> is a block diagram illustrating a first example of a schematic configuration of an eNB to which the technology according to the present disclosure may be applied. An eNB <NUM> includes one or more antennas <NUM> and a base station apparatus <NUM>. Each antenna <NUM> and the base station apparatus <NUM> may be connected to each other via an RF cable.

Each of the antennas <NUM> includes a single or a plurality of antenna elements (e.g. a plurality of antenna elements constituting a MIMO antenna) and is used for the base station apparatus <NUM> to transmit and receive a wireless signal. The eNB <NUM> may include the plurality of the antennas <NUM> as illustrated in <FIG>, and the plurality of antennas <NUM> may, for example, correspond to a plurality of frequency bands used by the eNB <NUM>. It should be noted that while <FIG> illustrates an example in which the eNB <NUM> includes the plurality of antennas <NUM>, the eNB <NUM> may include the single antenna <NUM>.

The base station apparatus <NUM> includes a controller <NUM>, a memory <NUM>, a network interface <NUM>, and a wireless communication interface <NUM>.

The controller <NUM> may be, for example, a CPU or a DSP, and operates various functions of an upper layer of the base station apparatus <NUM>. For example, the controller <NUM> generates a data packet from data in a signal processed by the wireless communication interface <NUM>, and transfers the generated packet via the network interface <NUM>. The controller <NUM> may generate a bundled packet by bundling data from a plurality of base band processors to transfer the generated bundled packet. The controller <NUM> may also have a logical function of performing control such as radio resource control, radio bearer control, mobility management, admission control, and scheduling. The control may be performed in cooperation with a surrounding eNB or a core network. The memory <NUM> includes a RAM and a ROM, and stores a program executed by the controller <NUM> and a variety of control data (such as, for example, terminal list, transmission power data, and scheduling data).

The network interface <NUM> is a communication interface for connecting the base station apparatus <NUM> to the core network <NUM>. The controller <NUM> may communicate with a core network node or another eNB via the network interface <NUM>. In this case, the eNB <NUM> may be connected to a core network node or another eNB through a logical interface (e.g. S1 interface or X2 interface). The network interface <NUM> may be a wired communication interface or a wireless communication interface for wireless backhaul. When the network interface <NUM> is a wireless communication interface, the network interface <NUM> may use a higher frequency band for wireless communication than a frequency band used by the wireless communication interface <NUM>.

The wireless communication interface <NUM> supports a cellular communication system such as long term evolution (LTE) or LTE-Advanced, and provides wireless connection to a terminal located within the cell of the eNB <NUM> via the antenna <NUM>. The wireless communication interface <NUM> may typically include a base band (BB) processor <NUM> and an RF circuit <NUM>. The BB processor <NUM> may, for example, perform encoding/decoding, modulation/demodulation, multiplexing/demultiplexing, and the like, and performs a variety of signal processing on each layer (e.g. L1, medium access control (MAC), radio link control (RLC), and packet data convergence protocol (PDCP)). The BB processor <NUM> may have part or all of the logical functions as described above instead of the controller <NUM>. The BB processor <NUM> may be a module including a memory having a communication control program stored therein, a processor to execute the program, and a related circuit, and the function of the BB processor <NUM> may be changeable by updating the program. The module may be a card or blade to be inserted into a slot of the base station apparatus <NUM>, or a chip mounted on the card or the blade. Meanwhile, the RF circuit <NUM> may include a mixer, a filter, an amplifier, and the like, and transmits and receives a wireless signal via the antenna <NUM>.

The wireless communication interface <NUM> may include a plurality of the BB processors <NUM> as illustrated in <FIG>, and the plurality of BB processors <NUM> may, for example, correspond to a plurality of frequency bands used by the eNB <NUM>. The wireless communication interface <NUM> may also include a plurality of the RF circuits <NUM>, as illustrated in <FIG>, and the plurality of RF circuits <NUM> may, for example, correspond to a plurality of antenna elements. <FIG> illustrates an example in which the wireless communication interface <NUM> includes the plurality of BB processors <NUM> and the plurality of RF circuits <NUM>, but the wireless communication interface <NUM> may include the single BB processor <NUM> or the single RF circuit <NUM>.

In the eNB <NUM> illustrated in <FIG>, the information acquisition unit <NUM> and the control unit <NUM> described above with reference to <FIG> may be mounted in the wireless communication interface <NUM>. Alternatively, at least some of the components may be mounted in the controller <NUM>. As an example, the eNB <NUM> may be equipped with a module including some or all components of the wireless communication interface <NUM> (for example, the BB processor <NUM>) and/or the controller <NUM>, and the information acquisition unit <NUM> and the control unit <NUM> may be mounted in the module. In this case, the module may store a program causing the processor to function as the information acquisition unit <NUM> and the control unit <NUM> (that is, a program causing the processor to perform the operation of the information acquisition unit <NUM> and the control unit <NUM>) and execute the program. As another example, the program causing the processor to function as the information acquisition unit <NUM> and the control unit <NUM> may be installed in the eNB <NUM>, and the wireless communication interface <NUM> (for example, the BB processor <NUM>) and/or the controller <NUM> may execute the program. As described above, the eNB <NUM>, the base station apparatus <NUM>, or the module may be provided as an apparatus including the information acquisition unit <NUM> and the control unit <NUM>, and the program causing the processor to function as the information acquisition unit <NUM> and the control unit <NUM> may be provided. A readable recording medium in which the program is recorded may be provided.

In addition, in the eNB <NUM> shown in <FIG>, the wireless communication unit <NUM> described with reference to <FIG> may be implemented by the wireless communication interface <NUM> (for example, the RF circuit <NUM>). Moreover, the antenna unit <NUM> may be implemented by the antenna <NUM>. In addition, the network communication unit <NUM> may be implemented by the controller <NUM> and/or the network interface <NUM>.

<FIG> is a block diagram illustrating a second example of a schematic configuration of an eNB to which the technology according to the present disclosure may be applied. An eNB <NUM> includes one or more antennas <NUM>, a base station apparatus <NUM>, and an RRH <NUM>. Each of the antennas <NUM> and the RRH <NUM> may be connected to each other via an RF cable. The base station apparatus <NUM> and the RRH <NUM> may be connected to each other by a high speed line such as optical fiber cables.

Each of the antennas <NUM> includes a single or a plurality of antenna elements (e.g. antenna elements constituting a MIMO antenna), and is used for the RRH <NUM> to transmit and receive a wireless signal. The eNB <NUM> may include a plurality of the antennas <NUM> as illustrated in <FIG>, and the plurality of antennas <NUM> may, for example, correspond to a plurality of frequency bands used by the eNB <NUM>. <FIG> illustrates an example in which the eNB <NUM> includes the plurality of antennas <NUM>, but the eNB <NUM> may include the single antenna <NUM>.

The base station apparatus <NUM> includes a controller <NUM>, a memory <NUM>, a network interface <NUM>, a wireless communication interface <NUM>, and a connection interface <NUM>. The controller <NUM>, the memory <NUM>, and the network interface <NUM> are the same as the controller <NUM>, the memory <NUM>, and the network interface <NUM> described with reference to <FIG>.

The wireless communication interface <NUM> supports a cellular communication system such as LTE and LTE-Advanced, and provides wireless connection to a terminal located in a sector corresponding to the RRH <NUM> via the RRH <NUM> and the antenna <NUM>. The wireless communication interface <NUM> may typically include a BB processor <NUM>. The BB processor <NUM> is the same as the BB processor <NUM> described with reference to <FIG> except that the BB processor <NUM> is connected to an RF circuit <NUM> of the RRH <NUM> via the connection interface <NUM>. The wireless communication interface <NUM> may include a plurality of the BB processors <NUM>, as illustrated in <FIG>, and the plurality of BB processors <NUM> may, for example, correspond to a plurality of frequency bands used by the eNB <NUM> respectively. <FIG> illustrates an example in which the wireless communication interface <NUM> includes the plurality of BB processors <NUM>, but the wireless communication interface <NUM> may include the single BB processor <NUM>.

The connection interface <NUM> is an interface for connecting the base station apparatus <NUM> (wireless communication interface <NUM>) to the RRH <NUM>. The connection interface <NUM> may be a communication module for communication on the high speed line which connects the base station apparatus <NUM> (wireless communication interface <NUM>) to the RRH <NUM>.

Further, the RRH <NUM> includes a connection interface <NUM> and a wireless communication interface <NUM>.

The connection interface <NUM> is an interface for connecting the RRH <NUM> (wireless communication interface <NUM>) to the base station apparatus <NUM>. The connection interface <NUM> may be a communication module for communication on the high speed line.

The wireless communication interface <NUM> transmits and receives a wireless signal via the antenna <NUM>. The wireless communication interface <NUM> may typically include the RF circuit <NUM>. The RF circuit <NUM> may include a mixer, a filter, an amplifier and the like, and transmits and receives a wireless signal via the antenna <NUM>. The wireless communication interface <NUM> may include a plurality of the RF circuits <NUM> as illustrated in <FIG>, and the plurality of RF circuits <NUM> may, for example, correspond to a plurality of antenna elements. <FIG> illustrates an example in which the wireless communication interface <NUM> includes the plurality of RF circuits <NUM>, but the wireless communication interface <NUM> may include the single RF circuit <NUM>.

In the eNB <NUM> illustrated in <FIG>, the information acquisition unit <NUM> and the control unit <NUM> described above with reference to <FIG> may be mounted in the wireless communication interface <NUM> and the wireless communication interface <NUM>. Alternatively, at least some of the components may be mounted in the controller <NUM>. As an example, the eNB <NUM> may be equipped with a module including some or all components of the wireless communication interface <NUM> (for example, the BB processor <NUM>) and/or the controller <NUM>, and the information acquisition unit <NUM> and the control unit <NUM> may be mounted in the module. In this case, the module may store a program causing the processor to function as the information acquisition unit <NUM> and the control unit <NUM> (that is, a program causing the processor to perform the operation of the information acquisition unit <NUM> and the control unit <NUM>) and execute the program. As another example, the program causing the processor to function as the information acquisition unit <NUM> and the control unit <NUM> may be installed in the eNB <NUM>, and the wireless communication interface <NUM> (for example, the BB processor <NUM>) and/or the controller <NUM> may execute the program. As described above, the eNB <NUM>, the base station apparatus <NUM>, or the module may be provided as an apparatus including the information acquisition unit <NUM> and the control unit <NUM>, and the program causing the processor to function as the information acquisition unit <NUM> and the control unit <NUM> may be provided. A readable recording medium in which the program is recorded may be provided.

<FIG> is a block diagram illustrating an example of a schematic configuration of a smartphone <NUM> to which the technology according to the present disclosure may be applied. The smartphone <NUM> includes a processor <NUM>, a memory <NUM>, a storage <NUM>, an external connection interface <NUM>, a camera <NUM>, a sensor <NUM>, a microphone <NUM>, an input device <NUM>, a display device <NUM>, a speaker <NUM>, a wireless communication interface <NUM>, one or more antenna switches <NUM>, one or more antennas <NUM>, a bus <NUM>, a battery <NUM>, and a secondary controller <NUM>.

The processor <NUM> may be, for example, a CPU or a system on chip (SoC), and controls the functions of an application layer and other layers of the smartphone <NUM>. The memory <NUM> includes a RAM and a ROM, and stores a program executed by the processor <NUM> and data. The storage <NUM> may include a storage medium such as semiconductor memories and hard disks. The external connection interface <NUM> is an interface for connecting the smartphone <NUM> to an externally attached device such as memory cards and universal serial bus (USB) devices.

The camera <NUM> includes an image sensor such as charge coupled devices (CCDs) and complementary metal oxide semiconductor (CMOS), and generates a captured image. The sensor <NUM> may include a sensor group including, for example, a positioning sensor, a gyro sensor, a geomagnetic sensor, and an acceleration sensor. The microphone <NUM> converts a sound that is input into the smartphone <NUM> to an audio signal. The input device <NUM> includes, for example, a touch sensor which detects that a screen of the display device <NUM> is touched, a key pad, a keyboard, a button, or a switch, and accepts an operation or an information input from a user. The display device <NUM> includes a screen such as liquid crystal displays (LCDs) and organic light emitting diode (OLED) displays, and displays an output image of the smartphone <NUM>. The speaker <NUM> converts the audio signal that is output from the smartphone <NUM> to a sound.

The wireless communication interface <NUM> supports a cellular communication system such as LTE or LTE-Advanced, and performs wireless communication. The wireless communication interface <NUM> may typically include the BB processor <NUM>, the RF circuit <NUM>, and the like. The BB processor <NUM> may, for example, perform encoding/decoding, modulation/demodulation, multiplexing/demultiplexing, and the like, and performs a variety of types of signal processing for wireless communication. On the other hand, the RF circuit <NUM> may include a mixer, a filter, an amplifier, and the like, and transmits and receives a wireless signal via the antenna <NUM>. The wireless communication interface <NUM> may be a one-chip module in which the BB processor <NUM> and the RF circuit <NUM> are integrated. The wireless communication interface <NUM> may include a plurality of BB processors <NUM> and a plurality of RF circuits <NUM> as illustrated in <FIG> illustrates an example in which the wireless communication interface <NUM> includes a plurality of BB processors <NUM> and a plurality of RF circuits <NUM>, but the wireless communication interface <NUM> may include a single BB processor <NUM> or a single RF circuit <NUM>.

Further, the wireless communication interface <NUM> may support other types of wireless communication system such as a short range wireless communication system, a near field communication system, and a wireless local area network (LAN) system in addition to the cellular communication system, and in this case, the wireless communication interface <NUM> may include the BB processor <NUM> and the RF circuit <NUM> for each wireless communication system.

Each antenna switch <NUM> switches a connection destination of the antenna <NUM> among a plurality of circuits (for example, circuits for different wireless communication systems) included in the wireless communication interface <NUM>.

Each of the antennas <NUM> includes one or more antenna elements (for example, a plurality of antenna elements constituting a MIMO antenna) and is used for transmission and reception of the wireless signal by the wireless communication interface <NUM>. The smartphone <NUM> may include a plurality of antennas <NUM> as illustrated in <FIG> illustrates an example in which the smartphone <NUM> includes a plurality of antennas <NUM>, but the smartphone <NUM> may include a single antenna <NUM>.

Further, the smartphone <NUM> may include the antenna <NUM> for each wireless communication system. In this case, the antenna switch <NUM> may be omitted from a configuration of the smartphone <NUM>.

The bus <NUM> connects the processor <NUM>, the memory <NUM>, the storage <NUM>, the external connection interface <NUM>, the camera <NUM>, the sensor <NUM>, the microphone <NUM>, the input device <NUM>, the display device <NUM>, the speaker <NUM>, the wireless communication interface <NUM>, and the secondary controller <NUM> to each other. The battery <NUM> supplies electric power to each block of the smartphone <NUM> illustrated in <FIG> via a feeder line that is partially illustrated in the figure as a dashed line. The secondary controller <NUM>, for example, operates a minimally necessary function of the smartphone <NUM> in a sleep mode.

In the smartphone <NUM> illustrated in <FIG>, the interference amount calculation unit <NUM>, the detection unit <NUM> and/or reporting unit <NUM> described above with reference to <FIG> may be mounted in the wireless communication interface <NUM>. Alternatively, at least some of the components may be mounted in the processor <NUM> or the secondary controller <NUM>. As an example, the smartphone <NUM> may be equipped with a module including some or all components of the wireless communication interface <NUM> (for example, the BB processor <NUM>), the processor <NUM>, and/or the secondary controller <NUM>, and the interference amount calculation unit <NUM>, the detection unit <NUM> and/or reporting unit <NUM> may be mounted in the module. In this case, the module may store a program causing the processor to function as the interference amount calculation unit <NUM>, the detection unit <NUM> and/or reporting unit <NUM> (that is, a program causing the processor to perform the operation of the interference amount calculation unit <NUM>, the detection unit <NUM> and/or reporting unit <NUM>) and execute the program. As another example, the program causing the processor to function as the interference amount calculation unit <NUM>, the detection unit <NUM> and/or reporting unit <NUM> may be installed in the smartphone <NUM>, and the wireless communication interface <NUM> (for example, the BB processor <NUM>), the processor <NUM>, and/or the secondary controller <NUM> may execute the program. As described above, the smartphone <NUM> or the module may be provided as an apparatus including the interference amount calculation unit <NUM>, the detection unit <NUM> and/or reporting unit <NUM>, and the program causing the processor to function as the interference amount calculation unit <NUM>, the detection unit <NUM> and/or reporting unit <NUM> may be provided. A readable recording medium in which the program is recorded may be provided.

In addition, in the smartphone <NUM> shown in <FIG>, the wireless communication unit <NUM> described with reference to <FIG> may be implemented by the wireless communication interface <NUM> (for example, the RF circuit <NUM>). Moreover, the antenna unit <NUM> may be implemented by the antenna <NUM>.

<FIG> is a block diagram illustrating an example of a schematic configuration of a car navigation apparatus <NUM> to which the technology according to the present disclosure may be applied. The car navigation apparatus <NUM> includes a processor <NUM>, a memory <NUM>, a global positioning system (GPS) module <NUM>, a sensor <NUM>, a data interface <NUM>, a content player <NUM>, a storage medium interface <NUM>, an input device <NUM>, a display device <NUM>, a speaker <NUM>, a wireless communication interface <NUM>, one or more antenna switches <NUM>, one or more antennas <NUM>, and a battery <NUM>.

The processor <NUM> may be, for example, a CPU or an SoC, and controls the navigation function and the other functions of the car navigation apparatus <NUM>. The memory <NUM> includes a RAM and a ROM, and stores a program executed by the processor <NUM> and data.

The GPS module <NUM> uses a GPS signal received from a GPS satellite to measure the position (e.g. latitude, longitude, and altitude) of the car navigation apparatus <NUM>. The sensor <NUM> may include a sensor group including, for example, a gyro sensor, a geomagnetic sensor, and a barometric sensor. The data interface <NUM> is, for example, connected to an in-vehicle network <NUM> via a terminal that is not illustrated, and acquires data such as vehicle speed data generated on the vehicle side.

The content player <NUM> reproduces content stored in a storage medium (e.g. CD or DVD) inserted into the storage medium interface <NUM>. The input device <NUM> includes, for example, a touch sensor which detects that a screen of the display device <NUM> is touched, a button, or a switch, and accepts operation or information input from a user. The display device <NUM> includes a screen such as LCDs and OLED displays, and displays an image of the navigation function or the reproduced content. The speaker <NUM> outputs a sound of the navigation function or the reproduced content.

The wireless communication interface <NUM> supports a cellular communication system such as LTE or LTE-Advanced, and performs wireless communication. The wireless communication interface <NUM> may typically include the BB processor <NUM>, the RF circuit <NUM>, and the like. The BB processor <NUM> may, for example, perform encoding/decoding, modulation/demodulation, multiplexing/demultiplexing, and the like, and performs a variety of types of signal processing for wireless communication. On the other hand, the RF circuit <NUM> may include a mixer, a filter, an amplifier, and the like, and transmits and receives a wireless signal via the antenna <NUM>. The wireless communication interface <NUM> may be a one-chip module in which the BB processor <NUM> and the RF circuit <NUM> are integrated. The wireless communication interface <NUM> may include a plurality of BB processors <NUM> and a plurality of RF circuits <NUM> as illustrated in <FIG> illustrates an example in which the wireless communication interface <NUM> includes a plurality of BB processors <NUM> and a plurality of RF circuits <NUM>, but the wireless communication interface <NUM> may be a single BB processor <NUM> or a single RF circuit <NUM>.

Further, the wireless communication interface <NUM> may support other types of wireless communication system such as a short range wireless communication system, a near field communication system, and a wireless LAN system in addition to the cellular communication system, and in this case, the wireless communication interface <NUM> may include the BB processor <NUM> and the RF circuit <NUM> for each wireless communication system.

Each of the antennas <NUM> includes one or more antenna elements (for example, a plurality of antenna elements constituting a MIMO antenna) and is used for transmission and reception of the wireless signal by the wireless communication interface <NUM>. The car navigation apparatus <NUM> includes a plurality of antennas <NUM> as illustrated in <FIG> illustrates an example in which the car navigation apparatus <NUM> includes a plurality of antennas <NUM>, but the car navigation apparatus <NUM> may include a single antenna <NUM>.

Further, the smartphone <NUM> may include the antenna <NUM> for each wireless communication system. In this case, the antenna switch <NUM> may be omitted from a configuration of the car navigation apparatus <NUM>.

The battery <NUM> supplies electric power to each block of the car navigation apparatus <NUM> illustrated in <FIG> via a feeder line that is partially illustrated in the figure as a dashed line. The battery <NUM> accumulates the electric power supplied from the vehicle.

In the car navigation apparatus <NUM> illustrated in <FIG>, the interference amount calculation unit <NUM>, the detection unit <NUM> and/or reporting unit <NUM> described above with reference to <FIG> may be mounted in the wireless communication interface <NUM>. Alternatively, at least some of the components may be mounted in the processor <NUM>. As an example, the car navigation apparatus <NUM> may be equipped with a module including some or all components of the wireless communication interface <NUM> (for example, the BB processor <NUM>), and the interference amount calculation unit <NUM>, the detection unit <NUM> and/or reporting unit <NUM> may be mounted in the module. In this case, the module may store a program causing the processor to function as the interference amount calculation unit <NUM>, the detection unit <NUM> and/or reporting unit <NUM> (that is, a program causing the processor to perform the operation of the interference amount calculation unit <NUM>, the detection unit <NUM> and/or reporting unit <NUM>) and execute the program. As another example, the program causing the processor to function as the interference amount calculation unit <NUM>, the detection unit <NUM> and/or reporting unit <NUM> may be installed in the car navigation apparatus <NUM>, and the wireless communication interface <NUM> (for example, the BB processor <NUM>) and/or the processor <NUM> may execute the program. As described above, the car navigation apparatus <NUM> or the module may be provided as an apparatus including the interference amount calculation unit <NUM>, the detection unit <NUM> and/or reporting unit <NUM>, and the program causing the processor to function as the interference amount calculation unit <NUM>, the detection unit <NUM> and/or reporting unit <NUM> may be provided. A readable recording medium in which the program is recorded may be provided.

In addition, in the car navigation apparatus <NUM> shown in <FIG>, the wireless communication unit <NUM> described with reference to <FIG> may be implemented by the wireless communication interface <NUM> (for example, the RF circuit <NUM>). Moreover, the antenna unit <NUM> may be implemented by the antenna <NUM>.

The technology of the present disclosure may also be realized as an in-vehicle system (or a vehicle) <NUM> including one or more blocks of the car navigation apparatus <NUM>, the in-vehicle network <NUM>, and a vehicle module <NUM>. In other words, the in-vehicle system (or a vehicle) <NUM> may be provided as a device which includes the interference amount calculation unit <NUM>, the detection unit <NUM> and/or reporting unit <NUM>. The vehicle side module <NUM> generates vehicle data such as vehicle speed, engine speed, and trouble information, and outputs the generated data to the in-vehicle network <NUM>.

Each apparatus and each process according to the embodiment of the present disclosure have been described above with reference to <FIG>.

According to the embodiment of the present disclosure, the base station <NUM> includes the information acquisition unit <NUM> that acquires information about a directional beam which is an interference source for the terminal apparatus <NUM> connected to the base station <NUM> (a neighbor base station of the base station <NUM>), from among a plurality of directional beams which can be formed by the base station <NUM>, the information being provided by the base station <NUM>, and the control unit <NUM> that decides an operation of the base station <NUM> regarding transmission of a signal over the directional beam on the basis of the information.

Accordingly, it is possible to further decrease interference of a directional beam between cells, for example.

Although an example is described in which the system is a system that is compliant with LTE, LTE-Advanced, or a communication scheme that conforms to them, the present disclosure is not limited to such an example. For example, the communication system may be a system that conforms to another communication standard.

Further, it is not always necessary to execute the processing steps in the processing in the present specification in chronological order in order described in the flowcharts or the sequence diagrams. For example, the processing steps in the above-described processing may be executed in order different from the order described in the flowcharts or the sequence diagrams or may be executed in parallel.

In addition, a computer program for causing a processor (for example, a CPU, a DSP, or the like) provided in a device of the present specification (for example, a base station, a base station apparatus or a module for a base station apparatus, or a terminal apparatus or a module for a terminal apparatus) to function as a constituent element of the device (for example, the information acquisition unit, the control unit, or the like) (in other words, a computer program for causing the processor to execute operations of the constituent element of the device) can also be created. In addition, a recording medium in which the computer program is recorded may also be provided. Further, a device that includes a memory in which the computer program is stored and one or more processors that can execute the computer program (a base station, a base station apparatus or a module for a base station apparatus, or a terminal apparatus or a module for a terminal apparatus) may also be provided. In addition, a method including an operation of the constituent element of the device (for example, the information acquisition unit, the communication control unit, or the like) is also included in the technology of the present disclosure.

Claim 1:
A communication apparatus (<NUM>) comprising:
a circuitry configured to
receive first information related to channel quality measurement about a directional beam from a terminal device (<NUM>) via another communication apparatus (<NUM>) serving the terminal device (<NUM>);
decide restriction on resources used for transmission of a reference signal over the directional beam on the basis of the the first information as an operation of the communication apparatus (<NUM>);
characterized in that the circuitry is configured to
decide, as the restriction, lengthening a period of transmission of the reference signal;
lengthen said period; and
notify the operation of the communication apparatus (<NUM>) to the other communication apparatus (<NUM>).