Transmitting apparatus, receiving apparatus and transmission power control method
View Patent ↗A transmitting apparatus, a receiving apparatus and a transmission power control method wherein even in a case of performing a transmission power control of multi-valued modulated symbols, the degradation of reception characteristic and that of network usage efficiency can be avoided. A power control instructing part ( 204 ) adjusts, based on an encoding rate and a modulation scheme in a case of applying a power control value, which maximizes the MIMO channel capacity, to each stream, the power control value of a stream, which is the most likely to be affected by a power estimation error, into a reference value, and then applies the adjustment value used for that adjustment to the other streams, that is, the streams that are not likely to be affected by the power estimation error. A power control part ( 205 ) performs a transmission power control in accordance with the power control value as adjusted by the power control instructing part ( 204 ).
1. A transmitting apparatus comprising:
an adjusting section that obtains feedback information including power control values for streams, adjusts a power control value for a stream that is the most sensitive to an influence of power estimation error, to a predetermined reference value and adjusts power control values for other streams using an adjustment value representing a difference between the power control value before the adjustment and the reference value; and
a controlling section that controls transmission power of each stream according to the adjusted power control values.
2. The transmitting apparatus according to claim 1 , wherein the adjusting section determines the stream that is the most sensitive to the influence of power estimation error based on modulation schemes and coding rates applied to the streams.
3. The transmitting apparatus according to claim 1 , further comprising a storing section that stores a same power control value as for a common pilot channel signal or a value obtained by multiplying a power control value by a reciprocal of a number of streams, as a transmission power specifying value,
wherein, when there is a stream sensitive to the influence of power estimation error, other than the stream that is the most sensitive to the influence of power estimation error, the adjusting section replaces a feed back power control value with the transmission power specifying value.
4. The transmitting apparatus according to claim 1 , wherein, when there is a stream satisfying required received quality, for which an excessive power control value is set, the adjusting section replaces the adjustment value with a value obtained by subtracting an offset value associated with the excess value from the adjustment value and adjusts all streams using the replaced adjustment value.
5. A wireless communication base station apparatus comprising the transmitting apparatus according to claim 1 .
6. A receiving apparatus comprising:
a channel estimating section that obtains a channel matrix by carrying out channel estimation using a common pilot channel signal;
a power control information generating section that calculates power control values for streams that maximize channel capacity under a predetermined condition using the channel matrix;
a quality Information generating section that finds received quality of each stream in case the power control values are applied to the streams using the channel matrix, and determines modulation schemes and coding rates applicable to each stream based on the calculated received quality; and
a feedback information generating section that transmits feedback information including the power control values, modulation schemes and coding rates to the transmitting apparatus according to claim 1 .
7. A receiving apparatus comprising:
a channel estimating section that obtains a channel matrix by carrying out channel estimation using a common pilot channel signal;
a power control information generating section that calculates power control values for streams that maximize channel capacity under a predetermined condition using the channel matrix;
a quality information generating section that finds received quality of each stream in case the power control values are applied to the streams using the channel matrix and determines modulation schemes and coding rates applicable to each stream based on the received quality;
an offset storing section that stores an excess value associated with offset values; and
a feedback information generating section that transmits feedback information including the power control values, modulation schemes, coding rates and the offset values to the transmitting apparatus according to claim 4 .
8. A wireless communication mobile station apparatus comprising the receiving apparatus according to claim 6 .
9. A transmission power control method comprising:
in a receiving apparatus:
calculating power control values for streams that maximize channel capacity under a predetermined condition using a channel matrix;
finding received quality of each stream in case the power control values are applied to the streams using the channel matrix, and determining modulation schemes and coding rates applicable to each stream based on the received quality; and
transmitting feedback information including the power control values, modulation schemes and coding rates to a transmitting apparatus, and
in the transmitting apparatus:
obtaining feedback information including the power control values for the streams from the receiving apparatus, adjusting a power control value for a stream that is the most sensitive, to an influence of power estimation error and adjusting power control values for other streams using an adjustment value representing a difference between the power control value before the adjustment and a reference value; and
controlling transmission power of the streams according to the adjusted power control values.
10. A wireless communication system comprising:
a receiving apparatus that comprises:
a channel estimating section that obtains a channel matrix by carrying out channel estimation using a common pilot channel signal;
a power control information generating section that calculates power control values for streams that maximize channel capacity under a predetermined condition using the channel matrix;
a quality information generating section that finds received quality of each stream in case the power control values are applied to the streams using the channel matrix, and determines modulation schemes and coding rates applicable to each stream based on the received quality; and
a feedback information generating section that transmits feedback information including the power control values, modulation schemes and coding rates to a transmitting apparatus, and
the transmitting apparatus comprises:
an adjusting section that obtains feedback information including the power control values for the streams from the receiving apparatus, adjusts a power control value for a stream that is the most sensitive to an influence of a power estimation error, to a reference value and adjusts power control values for other streams using an adjustment value representing a difference between the power control value before the adjustment and a reference value; and
a controlling section that controls transmission power of the streams according to the adjusted power control values.