Broadcast signal transmission method, broadcast signal transmission apparatus, broadcast signal reception method, and broadcast signal reception apparatus
Disclosed is a transmission scheme for transmitting a first modulated signal and a second modulated signal in the same frequency at the same time. According to the transmission scheme, a precoding weight multiplying unit multiplies a precoding weight by a baseband signal after a first mapping and a baseband signal after a second mapping and outputs the first modulated signal and the second modulated signal. In the precoding weight multiplying unit, precoding weights are regularly hopped.
1. A communication apparatus comprising:
control information generation circuitry which, in operation, generates control information for specifying one of a plurality of precoding methods to be used to generate first transmission symbols and second transmission symbols, wherein the plurality of precoding methods includes a first precoding method where a fixed precoding matrix is used, a second precoding method where a precoding matrix with a phase shift is used, an amount of the phase shift being switched periodically and a third precoding method for spatial multiplexing;
a precoder which, in operation, generates the first transmission symbols and the second transmission symbols by applying a precoding matrix to first modulated symbols and second modulated symbols based on the control information, wherein the phase shift is applied to one of the first modulated symbols and the second modulated symbols; and
a transmitter which, in operation, transmits the generated first transmission symbols and second transmission symbols from two or more antennas and transmits the generated control information.
2. The communication apparatus according to claim 1 , wherein the amount of the phase shift is switched symbol by symbol.
3. The communication apparatus according to claim 1 , wherein the transmitter, in operation, transmits the generated first transmission symbols and second transmission symbols in a same time period over a same frequency band.
4. The communication apparatus according to claim 1 , wherein when the control information indicates that the precoding matrix with the phase shift should not be used to generate the first and second transmission symbols, the precoder generates the first transmission symbols and the second transmission symbols by applying the precoding matrix to the first modulated symbols and the second modulated symbols without applying the phase shift.
5. A communication method comprising:
generating control information for specifying one of a plurality of precoding methods to be used to generate first transmission symbols and second transmission symbols, wherein the plurality of precoding methods includes a first precoding method where a fixed precoding matrix is used, a second precoding method where a precoding matrix with a phase shift is used, an amount of the phase shift being switched periodically and a third precoding method for spatial multiplexing;
generating the first transmission symbols and the second transmission symbols by applying a precoding matrix to first modulated symbols and second modulated symbols based on the control information, wherein the phase shift is applied to one of the first modulated symbols and the second modulated symbols; and
transmitting the generated first transmission symbols and second transmission symbols from two or more antennas and transmits the generated control information.
6. The communication method according to claim 5 , wherein the amount of the phase shift is switched symbol by symbol.
7. The communication method according to claim 5 , wherein the transmitting comprising transmitting the generated first transmission symbols and second transmission symbols in a same time period over a same frequency band.
8. The communication method according to claim 5 , wherein when the control information indicates that the precoding matrix with the phase shift should not be used to generate the first and second transmission symbols, the first transmission symbols and the second transmission symbols are generated by applying the precoding matrix to the first modulated symbols and the second modulated symbols without applying the phase shift.