Transmitting apparatus, receiving apparatus and multiplex number controlling method
A spatial multiplex number controlling method and others wherein streams can be separated for each of receivers and the transmission efficiency can be improved. In a receiving apparatus, a PER is calculated from a history of CRC test results per stream multiplex number. A reception quality and an offset corresponding to the calculated PER are fed back to a transmitting apparatus. The transmitting apparatus assigns, based on the fed-back reception quality and offset, the streams, thereby controlling the stream multiplex number.
1. A receiving apparatus comprising:
a receiving section that receives a signal comprised of streams which are spatially multiplexed;
a spatial demultiplexing capacity estimating section that estimates a capacity for demultiplexing the signal into the streams by detecting an error of the signal and obtaining an error rate for each of a plurality of multiplexing numbers, each multiplexing number being a number of the streams that are spatially multiplexed;
an offset setting section that sets an offset value for each of the multiplexing numbers, respectively, based on the obtained error rate using a predetermined association between the obtained error rate and the offset value, the offset values being used for controlling a first multiplexing number from among the multiplexing numbers;
a received quality measuring section that measures received quality of each of the streams; and
a feedback section that feeds back, to a transmitting apparatus, information indicating each of the offset values and the received quality.
2. The receiving apparatus according to claim 1 , wherein the spatial demultiplexing capacity estimating section comprises a memory that stores a record of an error detection result of the signal, the record of the error detection result being stored for each of the multiplexing numbers, and obtains the error rate calculated from the record.
3. The receiving apparatus according to claim 1 , wherein the spatial demultiplexing capacity estimating section comprises a memory that stores a record of an error detection result of the signal, the record of the error detection result being stored for a coding rate of each of the streams, and obtains the error rate calculated from the record.
4. The receiving apparatus according to claim 1 , wherein the spatial demultiplexing capacity estimating section calculates a tentative decision value of a symbol obtained by demodulating the signal, and estimates the capacity based on whether a square distance between the calculated tentative decision value and a candidate point exceeds a predetermined threshold value.
5. The receiving apparatus according to claim 1 , further comprising:
a predicting section that predicts, based on the received quality, the multiplexing number of the streams to be received by the receiving section; and
a memory that stores a record of an error detection result of the signal, for a difference between the predicted multiplexing number and a multiplexing number of the streams actually received by the receiving section.
6. A transmitting apparatus for communicating with a receiving apparatus that includes a receiving section that receives a signal comprised of streams which are spatially multiplexed; a spatial demultiplexing capacity estimating section that estimates a capacity for demultiplexing the signal into the streams by detecting an error of the signal and obtaining an error rate for each of a plurality of multiplexing numbers, each multiplexing number being a number of the streams that are spatially multiplexed; an offset setting section that sets an offset value for each of the multiplexing numbers, respectively, based on the obtained error rate using a predetermined association between the obtained error rate and the offset value, the offset values being used for controlling a first multiplexing number from among the multiplexing numbers; a received quality measuring section that measures received quality of each of the streams; and a feedback section that feeds back, to a transmitting apparatus, information indicating each of the offset values and the received quality, the transmitting apparatus comprising:
a stream assigning section that controls the first multiplexing number of the streams by obtaining the information indicating the offset values and the received quality, fed back from the receiving apparatus, and by carrying out an assignment of the streams based on the offset values and the received quality indicated by the obtained information; and
a transmission processing section that performs transmission processing of the signal comprised of the assigned streams which are spatially multiplexed.
7. The transmitting apparatus according to claim 6 , further comprising a symbol inserting section that inserts, into a transmission symbol, a known symbol for estimating the capacity for demultiplexing the signal into the streams in the receiving apparatus.
8. The transmitting apparatus according to claim 6 , further comprising a stream assignment adjusting section that determines the first multiplexing number of the streams and outputs the determined first multiplexing number of the streams to the stream assigning section.
9. A spatial multiplexing control method comprising:
at a receiving apparatus:
receiving a signal comprised of streams which are spatially multiplexed;
estimating a capacity for demultiplexing the signal into the streams by detecting an error of the signal and obtaining an error rate for each of a plurality of multiplexing numbers, each multiplexing number being a number of the streams that are spatially multiplexed;
setting an offset value for each of the multiplexing numbers, respectively, based on the obtained error rate using a predetermined association between the obtained error rate and the offset value, the offset values being used for controlling a first multiplexing number from among the multiplexing numbers;
measuring received quality of each of the streams; and
feeding back, to a transmitting apparatus, information indicating each of the offset values and the received quality, and
at the transmitting apparatus:
controlling the first multiplexing number of the streams by carrying out an assignment of the streams based on the information fed back from the receiving apparatus, indicating the offset values and the received quality fed back from the receiving apparatus.
10. A communication system comprising a receiving apparatus and a transmitting apparatus, wherein:
the receiving apparatus comprises:
a receiving section that receives a signal comprised of streams which are spatially multiplexed;
a spatial demultiplexing capacity estimating section that estimates a capacity for demultiplexing the signal into the streams;
an offset setting section that sets an offset value for each of a plurality of multiplexing numbers, respectively, based on an obtained error rate using a predetermined association between the obtained error rate and the offset value, the offset values being used for controlling a first multiplexing number from among the multiplexing numbers;
a received quality measuring section that measures received quality of each of the streams; and
a feedback section that feeds back, to the transmitting apparatus, information indicating each of the offset values and the received quality; and
the transmitting apparatus comprises:
a stream assigning section that controls the first multiplexing number of the streams by obtaining the information indicating the offset values and the received quality, fed back from the receiving apparatus, and by carrying out an assignment of the streams based on the offset values and the received quality indicated by the obtained information; and
a transmission processing section that performs transmission processing of the signal comprised of the assigned streams.