Method and apparatus for mitigating pilot pollution in a wireless network
First Claim
1. A method for wireless communication comprising:
- sending a common pilot at a first density and a first transmit power level during a first time period;
sending the common pilot at a second density and a second transmit power level during a second time period, the second density being lower than the first density, or the second transmit power level being lower than the first transmit power level, or both;
selecting a first modulation and coding scheme (MCS) for a terminal during the first time period;
selecting a second MCS for the terminal during the second time period, wherein the common pilot is used for channel estimation by the terminal, and wherein the second MCS is lower than the first MCS to account for degradation in channel estimation during the second time period; and
determining the first and second time periods based on signal-to-noise-and-interference ratios (SINRs) of terminals, the SINRs being high during the second time period and not high during the first time period.
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Accused Products
Abstract
Techniques for mitigating pilot pollution in a wireless network are described. In an aspect, pilot pollution may be mitigated by reducing density and/or transmit power of common pilots whenever possible. A cell may send a common pilot at a first density and a first transmit power level during a first time period and may send the common pilot at a second density and a second transmit power level during a second time period. The second density may be lower than the first density and/or the second transmit power level may be lower than the first transmit power level. Lower density may be achieved by sending the common pilot less frequently, on fewer subcarriers, and/or from fewer antennas. The cell may determine whether to reduce the density and/or transmit power of the common pilot based on network loading, SINRs of terminals, etc. In another aspect, pilot pollution may be mitigated by performing pilot cancellation at a terminal.
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Citations
22 Claims
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1. A method for wireless communication comprising:
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sending a common pilot at a first density and a first transmit power level during a first time period; sending the common pilot at a second density and a second transmit power level during a second time period, the second density being lower than the first density, or the second transmit power level being lower than the first transmit power level, or both; selecting a first modulation and coding scheme (MCS) for a terminal during the first time period; selecting a second MCS for the terminal during the second time period, wherein the common pilot is used for channel estimation by the terminal, and wherein the second MCS is lower than the first MCS to account for degradation in channel estimation during the second time period; and determining the first and second time periods based on signal-to-noise-and-interference ratios (SINRs) of terminals, the SINRs being high during the second time period and not high during the first time period. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. An apparatus for wireless communication, comprising:
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a transmitter configured to send a common pilot at a first density and a first transmit power level during a first time period, and to send the common pilot at a second density and a second transmit power level during a second time period, the second density being lower than the first density, or the second transmit power level being lower than the first transmit power level, or both; and at least one processor configured to select a first modulation and coding scheme (MCS) for a terminal during the first time period, and to select a second MCS for the terminal during the second time period, wherein the common pilot is used for channel estimation by the terminal, and wherein the second MCS is lower than the first MCS to account for degradation in channel estimation during the second time period; the at least one processor further configured to determine the first and second time periods based on signal-to-noise-and-interference ratios (SINRs) of terminals, the SINRs being high during the second time period and not high during the first time period. - View Dependent Claims (17, 18)
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19. An apparatus for wireless communication, comprising:
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means for sending a common pilot at a first density and a first transmit power level during a first time period; means for sending the common pilot at a second density and a second transmit power level during a second time period, the second density being lower than the first density, or the second transmit power level being lower than the first transmit power level, or both; means for selecting a first modulation and coding scheme (MCS) for a terminal during the first time period; means for selecting a second MCS for the terminal during the second time period, wherein the common pilot is used for channel estimation by the terminal, and wherein the second MCS is lower than the first MCS to account for degradation in channel estimation during the second time period; and means for determining the first and second time periods based on signal-to-noise-and-interference ratios (SINRs) of terminals, the SINRs being high during the second time period and not high during the first time period. - View Dependent Claims (20, 21)
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22. A computer program product, comprising:
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a non-transitory computer-readable medium comprising; code for causing at least one computer to send a common pilot at a first density and a first transmit power level during a first time period; code for causing the at least one computer to send the common pilot at a second density and a second transmit power level during a second time period, the second density being lower than the first density, or the second transmit power level being lower than the first transmit power level, or both; code for causing the at least one computer to select a first modulation and coding scheme (MCS) for a terminal during the first time period, and to select a second MCS for the terminal during the second time period, wherein the common pilot is used for channel estimation by the terminal, and wherein the second MCS is lower than the first MCS to account for degradation in channel estimation during the second time period; and code for causing the at least one computer to determine the first and second time periods based on signal-to-noise-and-interference ratios (SINRs) of terminals, the SINRs being high during the second time period and not high during the first time period.
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Specification