Wireless Transmitting Apparatus and Pre-Equalization Method Thereof
A wireless transmitting apparatus capable of improving the reception error rate of a wireless receiving apparatus. In the inventive apparatus, a channel estimating part ( 122 ) acquires a propagation path estimated value. A control part ( 113 ) determines whether an estimation precision of the acquired propagation path estimated value is equal to or greater than a predetermined level. A pre-equalization (PE) part applies PE based on the acquired propagation path estimated value to a transport signal if it is determined that the estimation precision is equal to or greater than the predetermined level. Otherwise, the pre-equalization (PE) part avoids the PE application to the transport signal. An RF part ( 117 ) transmits the transport signal to which PE has been applied, and transmits the transport signal for which the PE application has been avoided.
1 . A radio transmission apparatus comprising:
an acquisition section that acquires a propagation path estimation value;
a determination section that determines whether or not estimation accuracy of the acquired propagation path estimation value is equal to or above a predetermined level;
a pre-equalization section that applies pre-equalization based on the acquired propagation path estimation value to a transmission signal when the estimation accuracy is determined to be equal to or above said predetermined level and that avoids application of the pre-equalization to the transmission signal when the estimation accuracy is determined to be less than said predetermined level; and
a transmission section that transmits a transmission signal to which the pre-equalization is applied and a transmission signal for which the application of the pre-equalization is avoided.
2 . The radio transmission apparatus according to claim 1 , wherein said determination section determines that the estimation accuracy is equal to or above said predetermined level when reception quality is equal to or above a predetermined threshold, and determines that the estimation accuracy is less than said predetermined level when the reception quality is less than said predetermined threshold.
3 . The radio transmission apparatus according to claim 1 , wherein said determination section determines that the estimation accuracy is less than said predetermined level when a maximum Doppler frequency is equal to or above a predetermined threshold, and determines that the estimation accuracy is equal to or above said predetermined level when the maximum Doppler frequency is less than said predetermined threshold.
4 . The radio transmission apparatus according to claim 1 , further comprising a multiplexing section that multiplexes a known signal with the transmission signal when the application of pre-equalization to the transmission signal is avoided and that avoids the multiplexing of the known signal when the pre-equalization is applied to the transmission signal.
5 . The radio transmission apparatus according to claim 4 , wherein said pre-equalization section switches between application and avoidance of the pre-equalization per frame.
6 . The radio transmission apparatus according to claim 4 , wherein:
the transmission signal is superimposed on subcarriers; and
said pre-equalization section switches between application and avoidance of the pre-equalization per subcarrier.
7 . The radio transmission apparatus according to claim 6 , wherein, when the received level of the subcarrier on which the transmission signal is superimposed is equal to or below a predetermined value, said pre-equalization section avoids the application of pre-equalization to the transmission signal.
8 . The radio transmission apparatus according to claim 1 , further comprising:
a multiplexing section that multiplexes known signals with a first transmission signal to which the pre-equalization is applied and with a second transmission signal for which the application of pre-equalization is avoided, the first and second transmission signals being superimposed on different subcarriers; and
a control section that performs control for distributing total transmission power of the known signals the known signal of the first transmission signal and the known signal of the second transmission signal, wherein said control section causes the second transmission power distributed to the known signal of the second transmission signal to be greater than the first transmission power distributed to the known signal of the first transmission signal.
9 . The radio transmission apparatus according to claim 8 , wherein said control section sets the first transmission power to a minimum value necessary for compensating for distortion including a frequency offset or phase noise.
10 . The radio transmission apparatus according to claim 8 , wherein said control section sets the first transmission power to zero.
11 . A radio reception apparatus comprising:
an estimation section that estimates a propagation path characteristic using a received signal to acquire a propagation path estimation value;
a determination section that determines whether the received signal is one to which pre-equalization is applied or one for which application of pre-equalization is avoided; and
a compensation section that compensates for distortion of the received signal based on the acquired propagation path estimation value when the received signal is determined to be one for which application of pre-equalization is avoided and that avoids compensation for the distortion when the received signal is determined to be one to which pre-equalization is applied.
12 . The radio reception apparatus according to claim 11 , wherein said compensation section compensates for distortion in a frequency domain when the received signal is determined to be one for which application of pre-equalization is avoided and avoids the compensation for the distortion in the frequency domain when the received signal is determined to be one to which pre-equalization is applied.
13 . A pre-equalization method comprising the steps of:
acquiring a propagation path estimation value;
determining whether or not estimation accuracy of the acquired propagation path estimation value is equal to or above a predetermined level; and
applying pre-equalization to a transmission signal when the estimation accuracy of the acquired propagation path estimation value is determined to be equal to or above a predetermined level, and avoiding application of the pre-equalization to the transmission signal when the estimation accuracy is determined to be less than said predetermined level.