Method and apparatus for aligning interference using a feed forward index in a hierarchical cell communication system
First Claim
1. A communication method of a macro base station, the method comprising:
- calculating, at the macro base station, an inter-cell nulling matrix that nulls an interference channel between the macro base station and a first pico terminal corresponding to a first pico base station based on a reception beamforming vector of the first pico terminal, and that nulls an interference channel between the macro base station and a second pico terminal corresponding to a second pico base station based on a reception beamforming vector of the second pico terminal; and
calculating, at the macro base station, respective transmission beamforming vectors of macro terminals to remove interference that occurs among the macro terminals, using respective reception beamforming schemes of the macro terminals and the inter-cell nulling matrix.
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Abstract
Provided is an interference aligning method and apparatus that does not perform full feed-forwarding in a hierarchical cell communication. A macro base station may generate respective transmission beamforming vectors of macro terminals to null interference channels to pico terminals and to remove interference among the macro terminals. The effective interference channels are based on reception beamforming vectors of the pico terminals. The macro base station may transmit, to a macro terminal, a feed-forward indicator (FFI) indicating a method of transmitting information associated with a reception beamforming vector of the macro terminal. The macro terminal may obtain information associated with the reception beamforming vector based on the FFI.
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Citations
18 Claims
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1. A communication method of a macro base station, the method comprising:
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calculating, at the macro base station, an inter-cell nulling matrix that nulls an interference channel between the macro base station and a first pico terminal corresponding to a first pico base station based on a reception beamforming vector of the first pico terminal, and that nulls an interference channel between the macro base station and a second pico terminal corresponding to a second pico base station based on a reception beamforming vector of the second pico terminal; and calculating, at the macro base station, respective transmission beamforming vectors of macro terminals to remove interference that occurs among the macro terminals, using respective reception beamforming schemes of the macro terminals and the inter-cell nulling matrix. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A communication method of a terminal, the method comprising:
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receiving, from a base station, a feed-forward indicator (FFI) that indicates one mode from among multiple modes associated with a method of obtaining a reception beamforming vector of the terminal; obtaining, from the base station, information for determining the reception beamforming vector, based on a method corresponding to a mode indicated by the FFI; and determining the reception beamforming vector based on the obtained information, wherein the multiple modes include at least one of; a first mode to receive the reception beamforming vector, a second mode to obtain, using a demodulation reference signal(DM-RS), information associated with a serving channel that is based on a transmission beamforming vector of the base station, and to calculate the reception beamforming vector based on the information associated with the obtained serving channel, and a third mode to receive DM-RSs that are orthogonal to each other, and to calculate the reception beamforming vector based on the obtained DM-RSs. - View Dependent Claims (11, 12, 13)
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14. A base station to reduce interference on a pico terminal that is served by a pico base station, the base station comprising:
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a receiving unit configured to receive channel information, including a reception beamforming vector of the pico terminal; a beamforming determining unit configured to determine a transmission beamforming vector of one or more terminals served by the base station, to reduce interference on the pico terminal, and to calculate a reception beamforming vector of the one or more terminals, based on the respective transmission beamforming vector of the one or more terminals; and a transmitting unit configured to transmit, to the one or more terminals, a feed-forward indicator (FFI) indicating one of multiple modes of transmitting information associated with the reception beamforming vector. - View Dependent Claims (15, 16)
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17. A terminal served by a base station to reduce interference, the terminal comprising;
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a receiving unit configured to receive, from the base station, a feed-forward indicator (FFI) and information for obtaining a reception beamforming vector, wherein the FFI indicates one of a plurality of modes of obtaining the reception beamforming vector; and a determining unit configured to determine the reception beamforming vector based on the mode indicated by the FFI and the information for obtaining the reception beamforming vector, wherein; the receiving unit is further configured to receive the FFI indicating a second mode, and the information for obtaining the reception beamforming vector received from the base station comprises information associated with a resource to which a demodulation resource signal (DM-RS) is to be transmitted, the receiving unit is further configured to receive the DM-RS from the base station based on the information associated with the resource, and the determining unit is further configured to determine the reception beamforming vector based on the FR and the received DM-RS. - View Dependent Claims (18)
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Specification