Communication apparatus and communication system

Abstract

A communication apparatus includes a reference signal generating section, a transmitting section, a propagation estimating section, a first data acquiring section, and a decoding section. The reference signal generating section generates a first reference signal to enable a communicating party to estimate a propagation environment. The transmitting section transmits the first reference signal. The propagation estimating section estimates a first propagation estimation value of the propagation environment using a second reference signal transmitted from the communicating party. The first data acquiring section generates first data using the first propagation estimation value. The decoding section decodes a transmission signal encoded using a second propagation estimation value that is estimated by the communicating party using the first reference signal, to obtain second data using the first data.

The invention claimed is: 
     
       1. A communication apparatus, comprising:
 a reference signal generating section that generates a first reference signal to enable a communicating party to estimate a propagation environment; 
 a transmitting section that transmits the first reference signal; 
 a storing section that stores a known signal known between the apparatus and the communicating party 
 a propagation estimating section that obtains correlation between the known signal and a second reference signal transmitted from the communicating party, and generates a delay profile as an estimation value of propagation environment; 
 a first data acquiring section that reads out first data associated with the delay profile generated in the propagation estimating section, from a reference table that associates the delay profile with the first data; and 
 a decoding section that decodes a transmission signal encoded and transmitted using an estimation value of the propagation environment estimated by the communicating party using the first reference signal, to obtain second data using the first data read out by the first data acquiring section. 
 
     
     
       2. The communication apparatus according to  claim 1 , wherein the first data acquiring section calculates convolution of correlation between the known signal and the second reference signal, and a quantization vector stored in the reference table, and selects and reads out a vector code as the first data by performing metric calculation using the delay profile and the quantization vector subjected to the convolution. 
     
     
       3. The communication apparatus according to  claim 1 , wherein the first data acquiring section performs orthogonal conversion on the delay profile generated in the propagation estimating section to condense signal components, and reads out the first data using signal components. 
     
     
       4. A communication method, comprising:
 generating, in a first communication apparatus, a first reference signal to enable a second communication apparatus to estimate a propagation environment; 
 transmitting the first reference signal from the first communication apparatus to the second communication apparatus; 
 storing, in the first communication apparatus, a known signal known between the first communication apparatus and the second communication apparatus; 
 obtaining, in the first communication apparatus, correlation between the known signal and a second reference signal transmitted from the second communication apparatus, and generating, in the first communication apparatus, a delay profile as an estimation value of the propagation environment; 
 reading out, in the first communication apparatus, first data associated with the generated delay profile, from a reference table that associates the delay profile with the first data; and 
 decoding, in the first communication apparatus, a transmission signal encoded and transmitted using an estimation value of the propagation environment estimated by the second communication apparatus using the first reference signal, to second data using the first data read out. 
 
     
     
       5. A transmitting apparatus, comprising:
 a plurality of antennas configured to transmit a plurality of transmitting signals simultaneously using a same frequency, the plurality of antennas including a first antenna and a second antenna;   a storer configured to store a plurality of weighting coefficient sets; and   a weighter configured to generate the plurality of transmitting signals, wherein:   each of the transmitting signals is a non-multiplexed signal or is a multiplexed signal into which a plurality of data is multiplexed;   the multiplexed signal and the non-multiplexed signal are multiplied by one weighting coefficient set, selected from the plurality of weighting coefficient sets, for each of the transmitting signals;   each of the plurality of weighting coefficient sets includes a weighting coefficient for each antenna; and   the plurality of weighting coefficient sets are vectors having no correlation with each other.   
     
     
       6. The transmitting apparatus according to claim 5, wherein,
 the storer is configured to store a relationship between the plurality of weighting coefficient sets and a polarization code indicating polarization information obtained from the plurality of antennas, and   each weighting coefficient set is calculated based on the polarization code and includes the weighting coefficient for each antenna.   
     
     
       7. A receiving apparatus, comprising:
 a plurality of receiving antennas configured to receive signals transmitted from a transmitting apparatus, the plurality of receiving antennas including a first receiving antenna and a second receiving antenna; and   a demodulator configured to demodulate received signals received at the plurality of receiving antennas, wherein:   the received signals received at the plurality of receiving antennas include a plurality of transmitted signals transmitted from a plurality of transmitting antennas of the transmitting apparatus simultaneously;   each of the transmitted signals is different from each other by one weighting coefficient set selected from a plurality of weighting coefficient sets for each of the transmitted signals;   each of the plurality of weighting coefficient sets includes a weighting coefficient for each transmitting antenna;   the plurality of weighting coefficient sets are vectors having no correlation with each other; and   the plurality of transmitted signals includes a signal multiplied by a weighting coefficient set for transmitting a multiplexed signal from each of the transmitting antennas or a signal multiplied by a weighting coefficient set for transmitting a non-multiplexed signal from each of the transmitting antennas.   
     
     
       8. The receiving apparatus according to claim 7, wherein,
 each transmitting signal is a signal multiplied by a weighting coefficient included in the one weighting coefficient set selected from the plurality of weighting coefficient sets based on a polarization code indicating polarization information obtained from the plurality of receiving antennas.   
     
     
       9. A transmitting method, comprising:
 transmitting a plurality of transmitting signals simultaneously using a same frequency from a plurality of antennas including a first antenna and a second antenna;   storing a plurality of weighting coefficient sets; and   generating the plurality of transmitting signals, wherein:   each of the transmitting signals is a non-multiplexed signal or is a multiplexed signal into which a plurality of data is multiplexed;   the multiplexed signal and the non-multiplexed signal are multiplied by one weighting coefficient set, selected from the plurality of weighting coefficient set for each of the transmitting signals;   each of the plurality of weighting coefficient sets includes a weighting coefficient for each antenna; and   the plurality of weighting coefficient sets are vectors having no correlation with each other.   
     
     
       10. The transmitting method according to claim 9, wherein,
 the storing comprises storing a relationship between the plurality of weighting coefficient sets and a polarization code indicating polarization information obtained from the plurality of antennas, and   each weighting coefficient set is calculated based on the polarization code and includes the weighting coefficient for each antenna.   
     
     
       11. A receiving method, comprising:
 receiving signals transmitted from a transmitting apparatus, by a plurality of receiving antennas including a first receiving antenna and a second receiving antenna; and   demodulating received signals received at the plurality of receiving antennas, wherein:   the received signals received at the plurality of receiving antennas include a plurality of transmitted signals transmitted from a plurality of transmitting antennas of the transmitting apparatus simultaneously;   each of the transmitted signals is different from each other by one weighting coefficient set selected from a plurality of weighting coefficient sets for each of the transmitted signals;   each of the plurality of weighting coefficient sets includes a weighting coefficient for each transmitting antenna;   the plurality of weighting coefficient sets are vectors having no correlation with each other; and   the plurality of transmitted signals includes a signal multiplied by a weighting coefficient set for transmitting a multiplexed signal from each of the transmitting antennas or a signal multiplied by a weighting coefficient set for transmitting a non-multiplexed signal from each of the transmitting antennas.   
     
     
       12. The receiving method according to claim 11, wherein,
 each transmitting signal is a signal multiplied by a weighting coefficient included in one weighting coefficient set selected from the plurality of weighting coefficient sets based on a polarization code indicating polarization information obtained from the plurality of receiving antennas.