Method and apparatus using cell-specific and common pilot subcarriers in multi-carrier, multi-cell wireless communication networks

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 mobile station being associated with a serving base station in a serving cell within a group of cells in the system and having a receiver configured to receive different types of pilot subcarriers within a same frequency band that is divided into a plurality of subcarriers, the mobile station comprising:

• a facility configured for receiving cell-specific pilot subcarriers from the serving base station in the serving cell, wherein:
• the cell-specific pilot subcarriers possess characteristics specific to the serving 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 facility configured for receiving common pilot subcarriers from the serving base station and other base stations within the group of cells, wherein:
• common pilot subcarriers transmitted by the serving base station and the other base stations possess characteristics common to the group of cells;
• common pilot subcarriers transmitted by the serving base station are aligned in frequency subcarrier index with common pilot subcarriers transmitted by the other base stations in the group of cells;
• and
• frequency-domain signal randomization applied on the common pilot subcarriers transmitted by the serving base station is different from frequency-domain signal randomization applied on common pilot subcarriers transmitted by base stations in a different group of cells in the system.

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 signal transmission method for a base station in a cell within a group of cells in the system, the base station 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 method comprising:

• transmitting 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
• transmitting 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 cells within the group;
• 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 different from frequency-domain signal randomization applied on common pilot subcarriers transmitted by base stations in a different group of cells in the system.

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 signal reception method for a mobile station associated with a serving base station in a serving cell within a group of cells in the wireless communication system, the mobile station including a receiver configured to receive different types of pilot subcarriers within a same frequency band that is divided into a plurality of subcarriers, the method comprising:

• receiving cell-specific pilot subcarriers from the serving base station in the serving cell, wherein:
• the cell-specific pilot subcarriers possess characteristics specific to the serving 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
• receiving common pilot subcarriers from the serving base station and other base 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 cells within the group;
• common pilot subcarriers transmitted by the serving base station are aligned in frequency subcarrier index with common pilot subcarriers transmitted by the other base stations in the group of cells;
• and
• frequency-domain signal randomization applied on the common pilot subcarriers transmitted by the serving base station is different from frequency-domain signal randomization applied on common pilot subcarriers transmitted by base stations in a different group of cells in the system.