Patent ID: 8238303

Claim:
A method of allocating subcarriers to user terminals in an orthogonal frequency division multiplexing system, said method comprising: allocating a first set of subcarrier blocks selected from a set of non-overlapping subcarrier blocks to a first user terminal; allocating a second set of subcarrier blocks selected from said set of non-overlapping subcarrier blocks to a second user terminal, wherein the second set of subcarrier blocks includes at least one subcarrier block not allocated to said first user terminal, and at least one reused subcarrier block that is also allocated to said first user; assigning reference signals to said first and second user terminals to be transmitted in respective ones of said subcarrier blocks, each said reference signal comprising a base reference sequence and a linear phase rotation in the frequency domain applied to the base reference sequence; wherein the reference signals assigned the first and second user terminals in said reused subcarrier block use the same base reference sequence; and wherein the reference signals assigned the first and second user terminals in said reused subcarrier block have different linear phase rotations in the frequency domain.