Radio transmitter apparatus and modulation scheme selecting method
View Patent ↗A wireless transmission apparatus that can accurately select an optimal modulation scheme on a per block basis in a multi-carrier communication system in which block division of subcarriers and adaptive modulation are performed. In this wireless transmission apparatus, a propagation path characteristics acquisition section ( 107 ) acquires the average SNR and SNR dispersion for each block, which are estimated by a wireless reception apparatus ( 200 ), using received signals inputted from a reception RF section ( 106 ) and outputs these to an assignment section ( 108 ), the assignment section ( 108 ) selects a modulation scheme for each block based on the average SNR and SNR dispersion of each block inputted from the propagation path characteristics acquisition section ( 107 ), and modulation sections ( 101 - 1, 101 - 2, . . . , 101 -L) modulate multi-carrier signals included in each block, with the modulation scheme for each block selected by the assignment section ( 108 ).
1. A wireless transmission apparatus that performs adaptive modulation with a multicarrier signal formed with a plurality of blocks, each block including a plurality of subcarrier signals, the wireless transmission apparatus comprising:
a selection section that selects modulation schemes of the plurality of blocks on a per block basis; and
a modulation section that modulates the plurality of subcarrier signals in the plurality of blocks using the modulation schemes selected on a per block basis,
wherein the selection section selects the modulation schemes on a per block basis based on an average and a dispersion of values representing propagation path characteristics of each block.
2. The wireless transmission apparatus according to claim 1 , wherein the average of the values representing propagation path characteristics comprises an average of SNRs and the dispersion of said values representing propagation path characteristics comprises a dispersion of said SNRs.
3. The wireless transmission apparatus according to claim 2 , wherein the dispersion of the SNRs is determined from SNRs less than or equal to an average SNR.
4. The wireless transmission apparatus according to claim 1 , wherein the average of the values representing propagation path characteristics comprises an average of SNRs and the dispersion of the values representing propagation path characteristics comprises a dispersion of channel estimation values.
5. The wireless transmission apparatus according to claim 4 , wherein the dispersion of the channel estimation values is determined from channel estimation values less than or equal to an average channel estimation value.
6. The wireless transmission apparatus according to claim 1 , wherein the average of the values representing propagation path characteristics comprises an average of SNRs and the dispersion of the values representing propagation path characteristics comprises a dispersion of amplitudes of signals of pilot portions.
7. The wireless transmission apparatus according to claim 6 , wherein the dispersion of the amplitudes of the signals of pilot portions is determined from signals of pilot portions having amplitudes less than or equal to an average amplitude.
8. A modulation scheme selection method used in a wireless communication system where adaptive modulation is performed with a multicarrier signal formed with a plurality of blocks, each block including a plurality of subcarrier signals, the method comprising:
a selection step of selecting modulation schemes of the plurality of blocks on a per block basis; and
a modulation step of modulating the plurality of subcarrier signals in the plurality of blocks using the modulation schemes selected on a per block basis,
wherein the selection step selects the modulation schemes on a per block basis based on an average and a dispersion of values representing propagation path characteristics of each block.