Patent ID: 8432891

Claim:
In a multi-cell, Orthogonal Frequency Division Multiple Access (OFDMA) wireless communication system comprising a plurality of mobile stations and base stations in a plurality of groups of cells, a base station in a cell within a group of cells having a transmitter that is synchronized in time and frequency with transmitters of other base stations in the group of cells and configured for transmitting different types of pilot subcarriers within a same frequency band that is divided into a plurality of subcarriers, the base station comprising: a transmitter component that is configured to transmit cell-specific pilot subcarriers to enable reception of cell-specific data by mobile stations in the cell, wherein: the cell-specific pilot subcarriers possess characteristics specific to the cell; and at least some of the cell-specific pilot subcarriers are not aligned in frequency subcarrier index with cell-specific pilot subcarriers transmitted by another base station in the group of cells; and a transmitter component that is configured to transmit common pilot subcarriers to enable reception of common data by mobile stations in the group of cells, wherein: the common pilot subcarriers possess characteristics common to common pilot subcarriers transmitted by other base stations in the group of cells; the common pilot subcarriers are aligned in frequency subcarrier index with common pilot subcarriers transmitted by other base stations in the group of cells; and frequency-domain signal randomization is applied on the common pilot subcarriers, wherein the frequency-domain signal randomization on the common pilot subcarriers is selected to be the same within the group of cells and wherein the frequency-domain signal randomization on the common pilot subcarriers is selected to be different from frequency-domain signal randomization applied on common pilot subcarriers transmitted by base stations in a different group of cells in the system.