Decoding control information received over a control channel

Abstract

A User Equipment (UE) monitors a set of Physical Downlink Control Channel (PDCCH) candidates for control information received from a base station at subframe k. The set of PDCCH candidates to monitor are defined in terms of search spaces. The UE monitors a UE-specific search space, among the search spaces, at each of aggregation levels (L) of 1, 2, 4 and 8 control channel elements (CCEs), the CCE being a resource unit comprising a specific number of resource elements and used for transmission of the control information. The L CCEs correspond to a first PDCCH candidate among the set of PDCCH candidates of the search space at a subframe k are located at positions given by: L*{(Yk)mod(floor(C))}+i, wherein i=0, . . . , L−1, where Yk is defined by: Yk=(A*Yk−1+B) mod D. The variable C is determined based on the number of CCEs (NCCE) divided by the aggregation level (L), and A, B, and D are predetermined constant values predetermined regardless of the aggregation levels L. The UE decodes the control information of the PDCCH.

What is claimed is: 
     
         1 . A method for decoding control information by a User Equipment (UE), the method comprising:
 monitoring a set of Physical Downlink Control Channel (PDCCH) candidates for control information received from a base station at subframe k,   wherein the set of PDCCH candidates to monitor are defined in terms of search spaces,   wherein the UE monitors a UE-specific search space, among the search spaces, at each of aggregation levels (L) of 1, 2, 4 and 8 control channel elements (CCEs),   wherein the CCE is a resource unit comprising a specific number of resource elements and used for transmission of the control information,   wherein the ‘L’ CCEs corresponding to a first PDCCH candidate among the set of PDCCH candidates of the search space at a subframe k are located at positions given by:
     L *{( Y   k )mod(floor( C ))}+ i,  wherein  i= 0, . . . ,  L− 1, 
   wherein Y k  is defined by:
     Y   k =( A*Y   k−1   +B ) mod  D,    
   wherein the variable C is determined based on the number of CCEs (N CCE ) divided by the aggregation level (L),   wherein A, B, and D are predetermined constant values predetermined regardless of the aggregation levels (L); and   decoding the control information of the PDCCH.