Interference suppression apparatus, system, inter-base station control method and program
In a HetNet configuration in which plural small-sized second cells are disposed in a first cell, an amount of signal processing for suppressing interference from other cells with respect to a reception signal on an uplink line of a base station of any one of the cells is reduced. An interference suppression apparatus creates a first propagation-path response matrix including a plurality of first propagation-path responses from terminals of plural second cells to a first base station, creates a second propagation-path response matrix including a plurality of second propagation-path responses from terminals of plural second cells to plural second base stations, calculates plural reception weights based on the first propagation-path response matrix and an inverse matrix of the second propagation-path response matrix, and suppresses interference to an uplink of the first base station, based on a reception signal of the first base station, reception signals of the plural second base stations and the plural reception weights. The interference suppression apparatus sets to zero a second propagation-path response having an electric power of magnitude equal to or less than a predetermined threshold value or less than the threshold value among the plurality of the second propagation-path responses included in the second propagation-path response matrix before calculating the inverse matrix.
1 . An interference suppression apparatus for suppressing interference from terminals located in plural other cells to a base station of any one cell of a first cell and plural second cells in a cellular network configuration that uses a same frequency band and includes the first cell formed by a first base station and the plural second cells formed within the first cell by plural second base stations, the interference suppression apparatus comprising:
a matrix creation section that estimates a plurality of first propagation-path responses from plural terminals respectively located in the plural other cells to an antenna of the base station of the one cell, creates a first propagation-path response matrix including the plurality of the first propagation-path responses as elements, estimates a plurality of second propagation-path responses from plural terminals respectively located in the plural other cells to antennas of base stations of the plural other cells, and creates a second propagation-path response matrix including the plurality of the second propagation-path responses as elements;
a weight calculation section that calculates an inverse matrix of the second propagation-path response matrix, and calculates plural reception weights to be applied to reception signals received by the antennas of the base stations of the plural other cells, based on the first propagation-path response matrix and the inverse matrix of the second propagation-path response matrix; and
a reception-signal processing section that suppresses interference from plural terminals located in the plural other cells to an uplink of the base station of the one cell, based on a reception signal received by the antenna of the base station of the one cell, plural reception signals received by the antennas of the base stations of the plural other cells, and the plural reception weights, and
wherein, before starting an operation of the cellular network configuration, the interference suppression apparatus performs a pre-estimation process for the plurality of the second propagation-path responses between the small cells in advance, and pre-sets to zero a second propagation-path response that is expected to have a small contribution to the interference, among the plurality of the second propagation-path responses of the second propagation-path response matrix to be used for creating the second propagation-path response matrix in the matrix creation section, based on a result of the pre-estimation process, and
wherein, when operating the cellular network configuration, the matrix creation section does not estimate the second propagation-path response that is pre-set to zero among the plurality of the second propagation-path responses of the second propagation-path response matrix.
2 . The interference suppression apparatus according to claim 1 ,
wherein the one cell is the first cell,
wherein the base station of the one cell is the first base station,
wherein the other cells are the second cells, and
wherein the base stations of the other cells are the second base stations.
3 . The interference suppression apparatus according to claim 2 ,
wherein the matrix creation section modifies to zero a second propagation-path response in which the calculated value of the electric power is equal to or less than a predetermined threshold value Γ th or less than the threshold value Γ th , among the plurality of the second propagation-path responses that are not pre-set to zero.
4 . The interference suppression apparatus according to claim 2 ,
wherein the interference suppression apparatus estimates the plurality of the second propagation-path responses before the plural second base stations start an operation, and sets to zero a second propagation-path response in which the calculated value of the electric power of the second propagation-path response is equal to or less than a predetermined threshold value Γ th or less than the threshold value Γ th , among the plurality of the second propagation-path responses.
5 . The interference suppression apparatus according to claim 2 ,
wherein the interference suppression apparatus determines a second propagation-path response that is to be pre-set to zero, based on a positional relationship between the plural second base stations or a positional relationship between the plural second cells.
6 . The interference suppression apparatus according to claim 2 ,
wherein the interference suppression apparatus is provided in a common baseband processing section that is connected to each of a radio section of the first base station and radio sections of the plural second base stations via a communication line.
7 . A system of a cellular network configuration, comprising:
a first base station that forms a first cell; and
plural second base stations that respectively form plural second cells, each of the plural second cells having a smaller cell size than the first cell disposed within the first cell, and
wherein a same frequency band is used for a radio communication of a terminal located in the first cell and a radio communication of a terminal located in each of the plural second cells,
wherein the system comprises the interference suppression apparatus according to claim 2 .
8 . The interference suppression apparatus according to claim 1 ,
wherein the one cell is the second cell,
wherein the base station of the one cell is the second base station,
wherein the other cells are the first cell and other second cells, and
wherein the base stations of the other cells are the first base station and other second base stations.
9 . The interference suppression apparatus according to claim 8 ,
wherein the matrix creation section modifies to zero a second propagation-path response in which the calculated value of the electric power is equal to or less than a predetermined threshold value Γ th or less than the threshold value Γ th , among the plurality of the second propagation-path responses that are not pre-set to zero.
10 . The interference suppression apparatus according to claim 8 ,
wherein the interference suppression apparatus estimates the plurality of the second propagation-path responses before the plural second base stations start an operation, and sets to zero a second propagation-path response in which the calculated value of the electric power of the second propagation-path response is equal to or less than a predetermined threshold value Γ th or less than the threshold value Γ th , among the plurality of the second propagation-path responses.
11 . The interference suppression apparatus according to claim 8 ,
wherein the interference suppression apparatus determines a second propagation-path response that is to be pre-set to zero, based on a positional relationship between the plural second base stations or a positional relationship between the plural second cells.
12 . The interference suppression apparatus according to claim 8 ,
wherein the interference suppression apparatus is provided in a common baseband processing section that is connected to each of a radio section of the first base station and radio sections of the plural second base stations via a communication line.
13 . A system of a cellular network configuration, comprising:
a first base station that forms a first cell; and
plural second base stations that respectively form plural second cells, each of the plural second cells having a smaller cell size than the first cell disposed within the first cell, and
wherein a same frequency band is used for a radio communication of a terminal located in the first cell and a radio communication of a terminal located in each of the plural second cells,
wherein the system comprises the interference suppression apparatus according to claim 8 .
14 . The interference suppression apparatus according to claim 1 ,
wherein the matrix creation section modifies to zero a second propagation-path response in which the calculated value of the electric power is equal to or less than a predetermined threshold value Γ th or less than the threshold value Γ th , among the plurality of the second propagation-path responses that are not pre-set to zero.
15 . The interference suppression apparatus according to claim 1 ,
wherein the interference suppression apparatus estimates the plurality of the second propagation-path responses before the plural second base stations start an operation, and sets to zero a second propagation-path response in which the calculated value of the electric power of the second propagation-path response is equal to or less than a predetermined threshold value Γ th or less than the threshold value Γ th , among the plurality of the second propagation-path responses.
16 . The interference suppression apparatus according to claim 1 ,
wherein the interference suppression apparatus determines a second propagation-path response that is to be pre-set to zero, based on a positional relationship between the plural second base stations or a positional relationship between the plural second cells.
17 . The interference suppression apparatus according to claim 1 ,
wherein the interference suppression apparatus is provided in a common baseband processing section that is connected to each of a radio section of the first base station and radio sections of the plural second base stations via a communication line.
18 . A system of a cellular network configuration, comprising:
a first base station that forms a first cell; and
plural second base stations that respectively form plural second cells, each of the plural second cells having a smaller cell size than the first cell disposed within the first cell, and
wherein a same frequency band is used for a radio communication of a terminal located in the first cell and a radio communication of a terminal located in each of the plural second cells,
wherein the system comprises the interference suppression apparatus according to claim 1 .