Method and apparatus for performing communication in a wireless communication system

Abstract

A method and apparatus for performing communication in a wireless communication system are provided. The method includes identifying a transmission mode configured for a serving cell by a Base Station (BS), by a User Equipment (UE), identifying an antenna configuration of the BS by the UE, determining the number of bits for a Rank Indication (RI) representing the number of layers based on the transmission mode and the antenna configuration, and generating an RI using the determined number of bits and transmitting the RI in transmission resources of the serving cell to the BS by the.

What is claimed is: 
     
         1 .- 32 . (canceled) 
     
     
         33 . A method for performing communication in a wireless communication system, the method comprising:
 identifying, by a User Equipment (UE), a transmission mode configured for a serving cell by a Base Station (BS);   identifying, by the UE, an antenna configuration of the BS by the UE;   determining, by the UE, the number of bits for a Rank Indication (RI) representing the number of layers based on a Multiple Input Multiple Output (MIMO) capability for each band combination reported to the BS by the UE and the antenna configuration, if the transmission mode indicates a predetermined first transmission mode among a plurality of predetermined transmission modes; and   generating, by the UE, an RI using the determined number of bits and transmitting the RI in transmission resources of the serving cell to the BS.   
     
     
         34 . The method of  claim 33 , wherein the first transmission mode includes at least one transmission mode configurable by a BS that has a function of the MIMO capability for each band combination. 
     
     
         35 . The method of  claim 33 , wherein the determining of the number of bits for the RI comprises:
 identifying a MIMO capability for each of band combinations reported to the BS by the UE, if the transmission mode indicates a predetermined first transmission mode among a plurality of predetermined transmission modes:   determining the number of layers corresponding to the MIMO capability for a frequency band of the serving cell from among the MIMO capabilities for the band combinations;   
       determining the number of antenna ports based on the antenna configuration of the BS; and 
       determining the number of bits for the RI based on the smaller between the number of layers corresponding to the MIMO capability for the frequency band of the serving cell and the determined number of antenna ports. 
     
     
         36 . The method of  claim 33 , further comprising: 
       if the transmission mode is one of a transmission mode  4  and a transmission mode  8  among a plurality of predetermined transmission modes, determining the number of bits for the RI based on a MIMO capability of the UE related with a UE category reported to the BS by the UE and the antenna configuration,
 wherein the UE reports at least one UE category to the BS, wherein each of the reported UE category is associated with a MIMO capability. 
 
     
     
         37 . The method of  claim 36 , wherein if the UE has reported two or more UE categories, the UE takes a MIMO capability related with a UE category that was reported in a field that is used by a BS of a predetermined old release, wherein the predetermined old release is one of release 8 and release 9 of a Long Term Evolution (LTE) standard. 
     
     
         38 . The method of  claim 33 , further comprising:
 if the transmission mode does not indicate at least one transmission mode being configurable by a BS that has a function of the MIMO capability for each band combination among a plurality of predetermined transmission modes, determining the number of bits for the RI based on a MIMO capability for all frequency bands of the UE reported to the BS by the UE and the antenna configuration.   
     
     
         39 . The method of  claim 33 , wherein the antenna configuration of the BS is indicated to the UE via a Radio Resource Control (RRC) message. 
     
     
         40 . A method for performing communication in a wireless communication system, the method comprising:
 identifying, by a Base Station (BS), a transmission mode configured in a serving cell for a User Equipment (UE);   identifying an antenna configuration of the BS;   determining the number of bits for a Rank Indication (RI) representing the number of layers based on a Multiple Input Multiple Output (MIMO) capability for each band combination reported to the BS by the UE and the antenna configuration, if the transmission mode indicates a predetermined first transmission mode among a plurality of predetermined transmission modes; and   decoding the RI using the determined number of bits, upon receipt of the RI in transmission resources of the serving cell from the UE.   
     
     
         41 . The method of  claim 40 , wherein the first transmission mode includes at least one transmission mode configurable by a BS that understands the MIMO capability for each band combination. 
     
     
         42 . The method of  claim 40 , wherein the determining of the number of bits for the RI comprises:
 identifying a MIMO capability for each of band combinations reported to the BS by the UE, if the transmission mode indicates a predetermined first transmission mode among a plurality of predetermined transmission modes:   determining the number of layers corresponding to a MIMO capability for a frequency band of the serving cell from among the MIMO capabilities for the band combinations;   determining the number of antenna ports based on the antenna configuration of the BS; and   determining the number of bits for the RI based on the smaller between the number of layers corresponding to the MIMO capability for the frequency band of the serving cell and the determined number of antenna ports.   
     
     
         43 . The method of  claim 40 , further comprising:
 if the transmission mode is one of a transmission mode  4  and a transmission mode  8  among a purality of predetermined transmission modes, determining the number of bits for the RI based on the MIMO capability of the UE linked with a UE category reported to the BS by the UE and the antenna configuration,   wherein the UE reports at least one UE category to the BS, wherein each of the reported UE category is associated with a MIMO capability.   
     
     
         44 . The method of  claim 43 , wherein, if the UE has reported two or more UE categories, the UE takes a MIMO capability linked with a UE category that was reported in the field that is understood by a BS of a predetermined old release, wherein the predetermined old release is one of release 8 and release 9 of a Long Term Evolution (LTE) standard. 
     
     
         45 . The method of  claim 40 , further comprising:
 if the transmission mode does not indicate at least one transmission mode being configurable by a BS that understands the MIMO capability for each band combination among a plurality of predetermined transmission modes, determining the number of bits for the RI based on a MIMO capability for all frequency bands of the UE reported to the BS by the UE and the antenna configuration.   
     
     
         46 . The method of  claim 40 , wherein the antenna configuration of the BS is indicated to the UE via a Radio Resource Control (RRC) message. 
     
     
         47 . An apparatus of a User Equipment (UE) for performing communication in a wireless communication system, the apparatus comprising:
 a controller configured to identify a transmission mode configured for a serving cell by a Base Station (BS), to identify an antenna configuration of the BS, and to determine the number of bits for a Rank Indication (RI) representing the number of layers based on a Multiple Input Multiple Output (MIMO) capability for each band combination reported to the BS by the UE and the antenna configuration, if the transmission mode indicates a predetermined first transmission mode among a plurality of predetermined transmission modes; and   a transmitter configured to generate an RI using the determined number of bits and to transmit the RI in transmission resources of the serving cell to the BS.   
     
     
         48 . The apparatus of  claim 47 , wherein the first transmission mode includes at least one transmission mode configurable by a BS that understands the MIMO capability for each band combination. 
     
     
         49 . The apparatus of  claim 47 , wherein if the transmission mode indicates a predetermined first transmission mode among a plurality of predetermined transmission modes, the controller is further configured to identify a MIMO capability for each of band combinations reported to the BS by the UE, determine the number of layers corresponding to a MIMO capability for a frequency band of the serving cell from among the MIMO capabilities for the band combinations, determine the number of antenna ports based on the antenna configuration of the BS, and determine the number of bits for the RI based on the smaller between the number of layers corresponding to the MIMO capability for the frequency band of the serving cell and the determined number of antenna ports. 
     
     
         50 . The apparatus of  claim 47 , wherein, if the transmission mode is one of a transmission mode  4  and a transmission mode  8  among a plurality of predetermined transmission modes, the controller is further configured to determine the number of bits for the RI based on the MIMO capability of the UE linked with a UE category reported to the BS by the UE and the antenna configuration,
 wherein the UE reports at least one UE category to the BS, wherein each of the reported UE category is associated with a MIMO capability. 
 
     
     
         51 . The apparatus of  claim 47 , wherein if the UE has reported two or more UE categories, the controller is further configured to take a MIMO capability linked with a UE category that was reported in the field that is understood by a BS of a predetermined old release, wherein the predetermined old release is one of release 8 and release 9 of a Long Term Evolution (LTE) standard. 
     
     
         52 . The apparatus of  claim 47 , wherein if the transmission mode does not indicate at least one transmission mode being configurable by a BS that understands the MIMO capability for each band combination among a plurality of predetermined transmission modes, the controller is further configured to determine the number of bits for the RI based on a MIMO capability for all frequency bands of the UE reported to the BS by the UE and the antenna configuration. 
     
     
         53 . The apparatus of  claim 47 , wherein the antenna configuration of the BS is indicated to the UE via a Radio Resource Control (RRC) message. 
     
     
         54 . An apparatus of a Base Station (BS) for performing communication in a wireless communication system, the apparatus comprising:
 a controller configured to identify a transmission mode configured in a serving cell for a User Equipment (UE) by the BS, to identify an antenna configuration of the BS, and to determine the number of bits for a Rank Indication (RI) representing the number of layers based on a Multiple Input Multiple Output (MIMO) capability for each band combination reported to the BS by the UE and the antenna configuration, if the transmission mode indicates a predetermined first transmission mode among a plurality of predetermined transmission modes; and   a receiver configured to decode the RI using the determined number of bits, upon receipt of the RI in transmission resources of the serving cell from the UE.   
     
     
         55 . The apparatus of  claim 54 , wherein the first transmission mode includes at least one transmission mode configurable by a BS that understands the MIMO capability for each band combination. 
     
     
         56 . The apparatus of  claim 54 , wherein if the transmission mode indicates a predetermined first transmission mode among a plurality of predetermined transmission modes, the controller is further configured to identify a MIMO capability for each of band combinations reported to the BS by the UE, determine the number of layers corresponding to a MIMO capability for a frequency band of the serving cell from among the MIMO capabilities for the band combinations, determine the number of antenna ports based on the antenna configuration of the BS, and determine the number of bits for the RI based on the smaller between the number of layers corresponding to the MIMO capability for the frequency band of the serving cell and the determined number of antenna ports. 
     
     
         57 . The apparatus of  claim 54 , wherein if the transmission mode is one of a transmission mode  4  and a transmission mode  8  among a plurality of predetermined transmission modes, the controller is further configured to determine the number of bits for the RI based on the MIMO capability of the UE linked with a UE category reported to the BS by the UE and the antenna configuration,
 wherein the UE reports at least one UE category to the BS, wherein each of the reported UE category is associated with a MIMO capability. 
 
     
     
         58 . The apparatus of  claim 57 , if the UE has reported two or more UE categories, the controller is further configured to take a MIMO capability linked with a UE category that was reported in the field that is understood by a BS of a predetermined old release, wherein the predetermined old release is one of release 8 and release 9 of a Long Term Evolution (LTE) standard. 
     
     
         59 . The apparatus of  claim 54 , wherein if the transmission mode does not indicate at least one transmission mode being configurable by a BS that understands the MIMO capability for each band combination among a plurality of predetermined transmission modes, the controller is further configured to determine the number of bits for the RI based on a MIMO capability for all frequency bands of the UE reported to the BS by the UE and the antenna configuration. 
     
     
         60 . The apparatus of  claim 54 , wherein the antenna configuration of the BS is indicated to the UE via a Radio Resource Control (RRC) message.