Patent ID: 8462711

Claim:
A base station apparatus in a mobile communications system which uses orthogonal frequency division multiplexing (OFDM) for downlink, comprising: a unit which generates a first signal; a unit which generates a second signal; a unit which multiplexes the first signal and the second signal and maps the multiplexed signals to a sub-carrier to generate a transmit symbol; a mapping determining unit which determines a position of mapping the second signal to the sub-carrier, wherein the mapping determining unit determines the mapping position based on a cell ID or cell group ID, and a mapping pattern defined with a sequence f hop (j) having a two-stage structure; and wherein the mapping pattern defined with the sequence having the two-stage structure is defined by f hop (j)=a(x,j)+b(ID), wherein ID is the cell group ID or the cell ID, a(x,j) is a first-stage sequence including a random hopping pattern having arguments x and j, wherein x=floor(ID/6) and j is an integer from 0 to 9, and wherein b(ID)=ID % 6 is a second-stage sequence representing a fixed shift to the first-stage sequence a(x,j), and wherein the cell or cell group having the same hopping pattern is arranged in a neighboring manner in the first sequence.