RADIO TRANSMITTING APPARATUS, RADIO RECEIVING APPARATUS, WIRELESS COMMUNICATION METHOD, AND WIRELESS COMMUNICATION SYSTEM
A radio transmitting apparatus, a radio receiving apparatus, a wireless communication method and a wireless communication system wherein even when a channel correlation is large, the channel capacity and the feedback amount can be improved. In ST 401 , a receiving apparatus ( 200 ) determines that the channel correlation value exceeds a predetermined threshold value. In ST 402 , a transmitting apparatus ( 100 ) is instructed to perform 42 MIMO transmission. In ST 403 , the transmitting apparatus ( 100 ) determines a pair of antennas exhibiting the highest channel correlation. In ST 406 , the receiving apparatus ( 200 ) uses, based on the pair information, a channel matrix, which comprises channel estimation values, to calculate a delay shift amount. In ST 407 , the delay shift amount is fed back to the transmitting apparatus ( 100 ). In ST 408 , the transmitting apparatus ( 100 ) uses the pair information and delay shift amount to combine SDM and a cyclic sample delay diversity, thereby transmitting data.
1 . A wireless transmitting apparatus comprising:
a plurality of transmitting antennas;
a converting section that converts a transmission signal into transmission signals of a plurality of sequences;
a transmission controlling section that duplicates the transmission signals of the plurality of sequences on a per sequence basis;
a delay processing section that performs cyclic delay processing of the duplicated transmission signals; and
a transmitting section that respectively transmits the transmission signals of duplicated sources and the transmission signals to which the cyclic delay processing is applied, from the transmitting antennas.
2 . The wireless transmitting apparatus according to claim 1 , further comprising an antenna pair determining section that determines that a pair of the transmitting antennas respectively transmitting the transmission signals that are the duplicated sources and the transmission signals to which the cyclic delay processing is applied, on a per stream basis as an antenna pair of high channel correlation.
3 . The wireless transmitting apparatus according to claim 1 , wherein, based on information showing the pair of the transmitting antennas determined in a receiving apparatus which is a communicating party, the transmitting section respectively transmits the transmission signals of the duplicated sources and the transmission signals to which the cyclic delay processing is applied, from the transmitting antennas.
4 . The wireless transmitting apparatus according to claim 1 , wherein the delay processing section that applies the cyclic delay processing of amounts of delay shift calculated in the receiving apparatus which is the communicating party.
5 . The wireless transmitting apparatus according to claim 1 , wherein the delay processing section applies the cyclic delay processing of a greater amount of delay shift than a length of a cyclic prefix.
6 . A wireless receiving apparatus comprising:
a channel estimating section that performs a channel estimation using pilots transmitted from a transmitting apparatus which is a communicating party; and
an antenna pair determining section that determines a pair of the transmission antennas with a highest channel correlation calculated from a channel estimation value and feeds back pair information showing the determined pair of antennas to the transmitting apparatus.
7 . The wireless receiving apparatus according to claim 6 , further comprising a delay shift amount computing section that calculates a determinant of a channel matrix provided with the channel estimation value based on the antenna pair information, finds amounts of delay shift using the calculated channel matrix and feeds back the found amounts of delay shift to the transmitting apparatus.
8 . The wireless receiving apparatus according to claim 7 , wherein the delay shift amount computing section further comprising:
a combined channel matrix generating section that generates a channel matrix of combined channels from the channel estimation value based on the antenna pair information;
a determinant calculating section that calculates a channel determinant from the combined channel matrix; and
a delay shift amount calculating section that defines the channel determinant as an evaluation function and calculates the amounts of delay shift that maximize the evaluation function.
9 . A wireless communication method comprising:
a transmission controlling step of duplicating transmission signals of a plurality of sequences on a per sequence basis;
a delay processing step of applying cyclic delay processing of the duplicated transmission signals; and
a transmitting step of respectively transmitting the transmission signals of a duplicated sources and the transmission signals to which the cyclic delay processing is applied, from a plurality of transmitting antennas.
10 . A wireless communication system comprising:
a receiving apparatus that comprises:
a plurality of receiving antennas;
a channel estimating section that performs a channel estimation using pilots transmitted from a transmitting apparatus which is a communicating party; and
a delay shift amount computing section that calculates a determinant of a channel matrix provided with the channel estimation value based on the antenna pair information showing a pair of transmission antennas with a highest channel correlation calculated from a channel estimation value, finds amounts of delay shift using the calculated determinant and feeds back the found amounts of delay shift to the transmitting apparatus; and
a transmitting apparatus that comprises:
a plurality of transmitting antennas which numbers are greater than the receiving antennas;
a converting section that converts a transmission signal into transmission signals of a plurality of sequences;
a transmission controlling section that duplicates the transmission signals of the plurality of sequences on a per sequence basis;
a delay processing section that performs cyclic delay processing on the duplicated transmission signals, the cyclic delay processing of the amounts of delay shift fed back from the receiving apparatus; and
a transmitting section that, based on the pair information, respectively transmits the transmission signals of duplicated sources and the transmission signals to which the cyclic delay processing is applied, from the transmitting antennas.