Rate-adaptive multiple input/multiple output (MIMO) systems
View Patent ↗A rate-adaptive method of communicating over a multipath wireless communication system uses multiple links such that each end of a link uses multiple transmit and receive antennas. A number of independent streams that are to be transmitted for each link is determined based on an overall system performance measure. In addition, the system may also jointly determine the best modulation, coding, power control, and frequency assignment for each link, based on an overall system performance measure. In OFDM systems, the number of independent streams, as well as the modulation, coding, and power control, may be determined on a tone-by-tone basis based on an overall system performance measure.
1. A method executed in a mobile station that communicates with a base station, said mobile station having multiple mobile station antennas, and said base station having M base station antennas, M being an integer greater than one, said method comprising:
determining in said mobile station channel conditions between said mobile station antennas station and said base station antennas; and
sending a request to said base station, contents of said request based on said channel conditions, said request requesting said base station to send information coded for Co-Channel interference (CCI) suppression, Multiple-Input-Multiple-Output (MIMO) reception, or to send information coded for both CCI suppression and MIMO reception, said request requesting said base station to send a particular stream of information through multiple ones of said base station antennas when requesting information coded for said CCI suppression, and to send multiple different streams of information, each of the multiple different streams being sent over a different one of the base station antennas, when requesting information coded for said MIMO reception; where, when said determining concludes, by performing comparisons, that Signal-to-Interference-and-Noise Ratio (SINR) is higher than a preselected first threshold and channel fading correlation is lower than a preselected second threshold, said request is for MIMO reception, and where, when said determining concludes, by performing comparisons, that Signal-to-Interference-and-Noise Ratio (SINR) is not higher than a preselected first threshold or channel fading correlation is not lower than a preselected second threshold, said request is for CCI suppression.
2. A method executed in a mobile station that communicates with a base station, said mobile station having multiple mobile station antennas, and said base station having M base station antennas, M being an integer greater than one, said method comprising: determining in said mobile station channel conditions between said mobile station antennas station and said base station antennas; and sending a request to said base station, contents of said request based on said channel conditions, said request requesting said base station to send information coded for Co-Channel interference (CCI) suppression, Multiple-Input-Multiple-Output (MIMO) reception, or to send information coded for both CCI suppression and MIMO reception, said request requesting said base station to send a particular stream of information through multiple ones of said base station antennas when requesting information coded for said CCI suppression, and to send multiple different streams of information, each of the multiple different streams being sent over a different one of the base station antennas, when requesting information coded for said MIMO reception where when said determining concludes, by performing comparisons, that Signal-to-Interference-and-Noise Ratio (SINR) is higher than a preselected first threshold, and channel fading correlation is lower than a preselected second threshold, said request is for MIMO reception; when said determining concludes, by performing comparisons, that said (SINR) is lower than a preselected first threshold, or said channel fading correlation is higher than a preselected second threshold, said request is for CCI suppression; and when said determining concludes, by performing comparisons, that said (SINR) is moderate, and said channel fading correlation is moderate, said request is that said base station send a number of streams of information that is between 1 and M.
3. A method executed in a first station having a plurality of first station antennas that communicates with a second station having M second station antennas, M>1, the method comprising:
determining in said first station channel conditions between said first and said second stations;
in response to said channel conditions being determined to be first channel conditions, sending a request to said second station from said first station, said request requesting said second station send a particular stream of information through multiple ones of said second station antennas; and
in response to the channel conditions being determined to be second channel conditions said request requesting said second station send a plurality of different streams of information over respective ones of the second station antennas, the plurality of different streams being ≦M.
4. The method as recited in claim 3 wherein the first channel conditions correspond to high interference and the second channel conditions correspond to low interference.