Efficient CQI signaling in MIMO systems with variable numbers of beams

Abstract

The present invention relates to the signaling of channel quality information in a multi-beam transmission system, wherein a plurality of sets of channel quality information are transmitted for controlling the transmission rate on one of the beams, wherein each set of channel quality information is derived dependent on an assumed parameter of at least one other beam which could be transmitted, comprising selecting a parameter of the transmission of each of the sets of channel quality information dependent on the assumed parameter of the at least one other beam.

The invention claimed is: 
     
       1. A method of operating a communication system, said method comprising signaling channel quality information (CQI) in a multi-beam transmission system, wherein a number of beams simultaneously transmitted may vary, said method further comprising:
 transmitting a plurality of sequences of channel quality information CQI values for controlling transmission rate on at least one of the beams, 
 estimating channel quality by analyzing quality of transmission of each of the number of beams via a plurality of channel quality estimators; and 
 deriving each sequence of the plurality of sequences of CQI values based on an assumed parameter of each of the number of beams, each sequence depending on transmissions made on other beams of the number of beams, wherein said plurality of sequences includes at least a first sequence of channel quality information CQI values, which assumes no other beams being transmitted, and a second sequence of channel quality information CQI values, which assumes at least one other beam being transmitted, said second sequence of channel quality CQI values including at least one value lower than any of those in said first sequence of channel quality CQI values. 
 
     
     
       2. The method according to  claim 1 , said method comprising selecting a transmission parameter of the transmission of each sequence of the plurality of sequences of channel quality information CQI values based on the assumed parameters of each of the number of beams. 
     
     
       3. The method according to  claim 2 , wherein a the transmission parameter of a sequence of the plurality of sequences of channel quality information CQI values is at least one or more of the following:
 a rate of update of channel quality information CQI reports in the sequence; 
 a resolution of the channel quality information CQI reports in the sequence; 
 a coding scheme of a channel quality information CQI report in the sequence; or 
 a transmission power or modulation scheme used for the channel quality information CQI reports in the sequence. 
 
     
     
       4. The method according to  claim 1 ,
 wherein the first sequence of channel quality information CQI values to indicate a transmission rate that is supported on a first beam if no other beams are transmitted simultaneously; and 
 the first sequence of channel quality information values indicate a transmission rate that is supported on the first beam if a second beam is transmitted simultaneously using an assumed set of parameters. 
 
     
     
       5. The method according to claim  4  1, wherein the second sequence of channel quality information CQI values indicate a transmission rate that is supported on the first beam if a second beam is transmitted simultaneously using an assumed set of parameters. 
     
     
       6. The method according to claim  4  1, wherein further sequences of channel quality information CQI values indicate transmission rates supported on the first beam if the second beam was transmitted with one of: different sets of parameters, and or to indicate the transmission rates supported on the first beams if one or more further beams were transmitted with same or different sets of parameters. 
     
     
       7. The method according to  claim 5 , wherein the second sequence of the plurality of sequences of channel quality information CQI values and further sequences of channel quality information CQI values are transmitted by use of differential signaling with respect to another sequence of the plurality of sequences of channels quality information CQI values. 
     
     
       8. The method according to claim  5  1, wherein the assumed set of parameters comprises at least one is one or more of the following:
 a number of beams assumed to be transmitted; 
 an identify of the second beam or another beam or beams to be transmitted; 
 an identity of an intended receiving station for the second beam or another beam or beams to be transmitted, or 
 thea transmission power of at least one of the beams. 
 
     
     
       9. The method according to claim  5  1, wherein a transmission of the second sequence of the plurality of sequences of the CQI values coincides with a transmission of the CQI values of the first sequence. 
     
     
       10. A multi-beam transmission system, wherein said system comprises:
 means for: the system comprising;
 means for transmitting a plurality of sequences of channel quality information (CQI) values (CQI) for controlling the a transmission rate on one of the beams; and 
 means for estimating channel quality by analysing quality of transmission of each of thea number of beams via a plurality of channel quality estimators; wherein each sequence of the plurality of sequences of channel quality informationCQI values is derived based on an assumed parameter of each of the number of beams, each sequence depending on transmission made on other beams of the number of beams, wherein said plurality of sequences includes at least a first sequence of channel quality informationCQI values, which assumes no other beams being transmitted, and a second sequence of channel quality informationCQI values, which assumeassumes at least one other beam being transmitted, said second sequence of channel qualityCQI values including at least one value lower than any of those in said first sequence of channel qualityCQI values. 
 
 
     
     
       11. The multi-beam transmission system according to  claim 10 , comprising selecting a transmission parameter of the transmission of each sequence of the plurality of sequences of channel quality information CQI values based on the assumed parameters of each of the number of beams, and wherein the transmission parameter is one or more of:
 a rate of update of CQI reports in the sequence; 
 a resolution of the CQI reports in the sequence; 
 a coding scheme of a CQI report in the sequence; or 
 a transmission power or modulation scheme used for the CQI reports in the sequence. 
 
     
     
       12. A mobile station for use in a multi-beam transmission system according to  claim 10 , wherein:
 the first sequence of CQI values indicate a transmission rate supported on a first beam if no other beams are transmitted simultaneously; and 
 the first sequence of CQI values indicate a transmission rate supported on the first beam if a second beam is transmitted simultaneously using an assumed set of parameters. 
 
     
     
       13. The mobile station according to claim  12  10, wherein the second sequence of CQI values indicate a transmission rate supported on the first beam if the a second beam is transmitted simultaneously using an assumed set of parameters. 
     
     
       14. The mobile station according to claim  12  13, wherein further sequences of said plurality of sequences of CQI values indicate transmission rates supported on the first beam if the second beam was transmitted with one of: different sets of parameters and or to indicate transmission rates supported on the first beam if further beams were transmitted with the same or different sets of parameters. 
     
     
       15. The mobile station according to  claim 12 , wherein said mobile station is configured to take into account beams transmitted to other mobile stations if they are transmitted using the same time, frequency and code resources. 
     
     
       16. The mobile station according to claim  12  13, wherein the CQI values reported for the first beam will have a different value depending on whether the second beam is assumed to be transmitted to a same or different mobile station as the first beam. 
     
     
       17. The mobile station according to  claim 16 , wherein the second beam is transmitted to the same mobile station as the first beam and wherein the mobile station reports a lower CQI value for the first beam, thereby enabling a higher CQI value to be reported for the second beam. 
     
     
       18. The mobile station according to claim  17  16, wherein the second beam is transmitted to a different mobile station than the first beam and wherein the mobile station reports a higher CQI value for the first beam than for the second beam. 
     
     
       19. A computer program stored on a non-transitory computer readable medium for executing the steps; comprising having stored thereon computer executable instructions configured to cause computer circuitry to:
 signallingsignal channel quality information (CQI) in a multi-beam transmission system, wherein a number of beams simultaneously transmitted may vary, said method further comprising:; 
 transmittingtransmit a plurality of sequences of channel quality informationCQI values for controlling transmission rate on at least one of the beams; 
 estimatingestimate channel quality by analysing quality of transmission of each of the number of beams via a plurality of channel quality estimators; and 
 derivingderive each sequence of the plurality of sequences of CQI values based on an assumed parameter of each of the number of beams, each sequence depending on transmission made on other beams of the number of beams, wherein said plurality of sequences includes at least a first sequence of channel quality informationCQI values, which assumes no other beams being transmitted, and a second sequence of channel quality informationCQI values, which assumeassumes at least one other beam being transmitted, said second sequence of channel qualityCQI values including at least one value lower than any of those in said first sequence of channel qualityCQI values. 
 
     
     
       20. A mobile station for use in a multi-beam transmission system, the mobile station comprising:
 a transmitter configured to transmit a plurality of sequences of channel quality information (CQI) values for controlling a transmission rate on one of a plurality of beams; and   a plurality of channel quality estimators configured to estimate channel quality by analysing quality of transmission of each of the plurality of beams; wherein each sequence of the plurality of sequences of CQI values is derived based on an assumed parameter of each of the plurality of beams, each sequence being derived based on transmission made on other beams of the plurality of beams, wherein said plurality of sequences includes at least a first sequence of CQI values, which assumes no other beams being transmitted, and a second sequence of CQI values, which assumes at least one other beam being transmitted, said second sequence of CQI values including at least one value lower than any of those in said first sequence of CQI values.   
     
     
       21. The mobile station according to claim 20, further comprising a control unit configured to select a transmission parameter of each sequence of the plurality of sequences of CQI values based on the assumed parameters of each of the number of beams, and wherein the transmission parameter is one or more of:
 a rate of update of CQI reports in the sequence;   a resolution of the CQI reports in the sequence;   a coding scheme of a CQI report in the sequence; or   a transmission power or modulation scheme used for the CQI reports in the sequence.   
     
     
       22. The mobile station according to claim 20, wherein:
 the first sequence of CQI values indicate a transmission rate supported on a first beam if no other beams are transmitted simultaneously.   
     
     
       23. The mobile station according to claim 20, wherein the second sequence of CQI values indicate a transmission rate supported on the first beam if a second beam is transmitted simultaneously using an assumed set of parameters. 
     
     
       24. The mobile station according to claim 23, wherein further sequences of said plurality of sequences of CQI values indicate transmission rates supported on the first beam if the second beam was transmitted with different sets of parameters or to indicate transmission rates supported on the first beam if further beams were transmitted with the same or different sets of parameters. 
     
     
       25. The mobile station according to claim 23, wherein said mobile station is configured to take into account beams transmitted to other mobile stations if they are transmitted using the same time, frequency and code resources. 
     
     
       26. The mobile station according to claim 23, wherein the CQI values reported for the first beam will have a different value depending on whether the second beam is assumed to be transmitted to a same or different mobile station as the first beam. 
     
     
       27. The mobile station according to claim 26, wherein the second beam is transmitted to the same mobile station as the first beam, and wherein the mobile station reports a lower CQI value for the first beam, thereby enabling a higher CQI value to be reported for the second beam. 
     
     
       28. The mobile station according to claim 27, wherein the second beam is transmitted to a different mobile station than the first beam and wherein the mobile station reports a higher CQI value for the first beam than for the second beam. 
     
     
       29. A mobile station for use in a multi-beam transmission system, the mobile station comprising:
 a transmitter configured to transmit a plurality of sequences of channel quality information (CQI) values for controlling a transmission rate on one of a plurality of beams, wherein each sequence of CQI values is derived based on an assumed parameter of at least one other beam; and   a computer processor configured to transmit, via the transmitter, a first sequence of CQI values to indicate a transmission rate supported on a first beam when no other beams are transmitted simultaneously and to transmit a second sequence of CQI values to indicate a transmission rate supported on the first beam if a second beam is transmitted simultaneously using an assumed set of parameters.   
     
     
       30. The mobile station according to claim 29, wherein the computer processor is configured to select a transmission parameter of each sequence of the plurality of sequences of CQI values based on the assumed parameters of each of the number of beams. 
     
     
       31. The mobile station according to claim 29, wherein the transmission parameter is one or more of
 a rate of update of CQI reports in the sequence;   a resolution of the CQI reports in the sequence;   a coding scheme of a CQI report in the sequence; or   a transmission power or modulation scheme used for the CQI reports in the sequence.   
     
     
       32. The mobile station according to claim 29, wherein the computer processor is configured to transmit, via the transmitter, further sequences of CQI values to indicate transmission rates supported on the first beam if the second beam was transmitted with different sets of parameters or to indicate transmission rates supported on the first beam if further beams were transmitted with the same or different sets of parameters. 
     
     
       33. The mobile station according to claim 29, wherein the computer processor is further configured to take into account beams transmitted to other mobile stations when they are transmitted using the same time, frequency and code resources. 
     
     
       34. A mobile station for use in a multi-beam transmission system, the mobile station comprising:
 a receiver configured to receive a plurality of transmitted beams;   a plurality of channel quality estimators configured to analyze a quality of transmission of the received plurality of transmitted beams and generate a set of assumed transmission parameters corresponding to each of the received plurality of beams;   a control unit configured to obtain the set of assumed transmission parameters from the plurality of channel estimators;   a plurality of CQI sequence units configured to generate a plurality of CQI sequences based on the set of assumed transmission parameters; and   a transmitter configured to transmit the plurality of CQI sequences including a first CQI sequence and a second CQI sequence, wherein the first sequence of CQI values indicate a transmission rate supported on a first beam when no other beams are transmitted simultaneously and the second sequence of CQI values indicate a transmission rate supported on the first beam if a second beam is transmitted simultaneously using the assumed set of transmission parameters.   
     
     
       35. The mobile station according to claim 34, wherein a CQI value of a first beam transmitted to a mobile station will vary depending on whether the second beam is transmitted to the mobile station or to a different mobile station. 
     
     
       36. The mobile station according to claim 35, wherein the mobile station reports a lower CQI value for the first beam when the second beam is transmitted to the mobile station. 
     
     
       37. The mobile station according to claim 35, wherein the mobile station reports a higher CQI value for the first beam when the second beam is transmitted to the different mobile station. 
     
     
       38. A multi-beam transmission system comprising:
 a base station configured to transmit a plurality of beams; and   a mobile station wherein the mobile station comprises:   a receiver configured to receive a plurality of transmitted beams;   a plurality of channel quality estimators configured to analyze a quality of transmission of the received plurality of transmitted beams and generate a set of assumed transmission parameters corresponding to each of the received plurality of beams;   a control unit configured to obtain the set of assumed transmission parameters from the plurality of channel estimators and generate a set of parameters for CQI sequences;   a plurality of Channel Quality Information (CQI) sequence units configured to generate a plurality of CQI sequences based on the set of assumed transmission parameters and the set of parameters for CQI sequences; and   a transmitter configured to transmit a plurality of CQI sequences including a first CQI sequence and a second CQI sequence, wherein the first sequence of CQI values indicate a transmission rate supported on a first beam when no other beams are transmitted simultaneously and the second sequence of CQI values indicate a transmission rate supported on the first beam if a second beam is transmitted simultaneously using an assumed set of parameters, and   wherein the base station receives the plurality of CQI sequences and transmits a next plurality of beams based on the plurality of CQI sequences received.   
     
     
       39. A mobile station for use in a multi-beam transmission system, the mobile station comprising:
 a plurality of antennas; and   a transmitter, coupled to the plurality of antennas and configured to transmit a plurality of sequences of channel quality information (CQI) values for controlling a transmission rate on a beam,   wherein the CQI values are estimated by analysing quality of transmission of each of a number of beams,   wherein each sequence of the plurality of sequences of CQI values is derived based on an assumed parameter of each of the number of beams, each sequence depending on a transmission on other beams of the number of beams,   wherein said plurality of sequences includes at least a first sequence of CQI values which assumes no other beams being transmitted, and a second sequence of CQI values which assumes at least one other beam being transmitted simultaneously,   said second sequence of CQI values including at least one value lower than any of those in said first sequence of CQI values.   
     
     
       40. The mobile station according to claim 39, comprising selecting a transmission parameter of the transmission of each sequence of the plurality of sequences of CQI values based on the assumed parameters of each of the number of beams. 
     
     
       41. The mobile station according to claim 39, wherein further sequences of said plurality of sequences of CQI values indicate transmission rates supported on the first beam if the second beam was transmitted with different sets of parameters or to indicate transmission rates supported on the first beam if further beams were transmitted with the same or different sets of parameters. 
     
     
       42. The mobile station according to claim 39, wherein said mobile station is configured to take into account beams transmitted to other mobile stations if they are transmitted using the same time, frequency and code resources. 
     
     
       43. The mobile station according to claim 39, wherein the CQI values reported for the first beam will have a different value depending on whether the second beam is assumed to be transmitted to a same or different mobile station as the first beam. 
     
     
       44. The mobile station according to claim 39, wherein the second beam is transmitted to the same mobile station as the first beam and wherein the mobile station reports a lower CQI value for the first beam, thereby enabling a higher CQI value to be reported for the second beam. 
     
     
       45. The mobile station according to claim 39, wherein the second beam is transmitted to a different mobile station than the first beam and wherein the mobile station reports a higher CQI value for the first beam than for the second beam.