Mobile communications in a hierarchical cell structure

A method for use in a cellular communications system that includes a macro cell encompassing a smaller micro cell, the macro cell including a macro cell base station and the micro cell including a micro cell base station, comprising:

• determining whether a condition in the system indicates that a downlink micro cell boundary between the macro cell and the micro cell, wherein the downlink cell boundary is associated with an effective range of a transmission from the micro cell base station, and an uplink micro cell boundary between the macro cell and the micro cell should be unbalanced wherein the uplink cell boundary is associated with a range of transmission from a mobile station to the micro cell base station,
• if the condition is met, reducing the downlink micro cell boundary to effect an unbalance between the uplink and downlink microcell boundaries,
• employing an offset to reduce a detected power level of a pilot transmitted by the micro cell base station, and
• transmitting a command to one or more mobile stations in the system to reduce a detected power level of a pilot transmitted by the micro cell base station by an offset amount included in the command.

Apparatus for use in a cellular communications system that includes a macro cell encompassing a smaller micro cell, comprising:

• means for determining and establishing an uplink communication cell boundary between the macro cell and the micro cell, and
• means for determining and establishing a downlink communication cell boundary
• between the macro cell and the micro cell different from the uplink communication cell boundary,
• wherein the uplink communication cell boundary is larger than the downlink communication cell boundary, the apparatus further comprising:
• means for determining whether an uplink interference level at the micro cell base station exceeds a threshold, and if so, performing an interference cancellation operation at a receiver at the micro cell to compensate for the uplink interference level,
• wherein the mean for determining is configured to determine whether to compensate for intra-cell uplink interference in the micro cell;
• and to detect one or more parameters regarding one or more mobiles on the macro cell side of the downlink communication cell boundary;
• and
• wherein the means for performing is configured to provide the one or more parameters for use in uplink interference cancellation in the micro cell.

A node for use in a cellular communications system that includes a macro cell encompassing a smaller micro cell, the macro cell including a macro cell base station and the micro cell including a micro cell base station, comprising:

• a supervisory controller configured to control one or more operations of the macro cell base station and the micro cell base station, and
• a link balance controller, coupled to the supervisory controller, configured to determine whether a condition indicates that an unbalanced link should be implemented between a downlink micro cell boundary between the macro cell, wherein the downlink cell boundary is associated with an effective range of a transmission from the micro cell base station, and the micro cell and an uplink micro cell boundary between the macro cell and the micro cell, wherein the uplink cell boundary is associated with a range of transmission from a mobile station to the micro cell base station, and if so, to reduce the downlink micro cell boundary to implement the unbalanced link
• wherein the link balance controller is further configured to employ an offset to reduce a detected power level of a pilot transmitted by the micro cell base station and to transmit a command to one or more mobile stations in the system to reduce a detected power level of a pilot transmitted by the micro cell base station by an offset amount included in the command.