Radio network environment reducing interference among overlapping cells

• US 9,380,591 B2
• Filed: 04/24/2015
• Issued: 06/28/2016
• Est. Priority Date: 08/04/2009
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Inventors: Xu, Ning, Yang, Jin
• Primary Examiner(s): Eng, George
• Assistant Examiner(s): HAMMONDS, MARCUS C
• Application Number:
  US14/695,502
• Publication Number:
  US 20150230262A1
• Time in Patent Office: 431 Days
• US Class Current: 1/1
• CPC Class Codes: H04W 16/02 Resource partitioning among network components, e.g. reuse partitioning
• CPC Class Codes: H04W 72/0453 Resources in frequency domain, e.g. a carrier in FDMA
• CPC Class Codes: H04W 72/27 between access points
• CPC Class Codes: H04W 72/541 using the level of interference
• CPC Class Codes: H04W 84/045 using private Base Stations, e.g. femto Base Stations, home Node B

Abstract

Disclosed is a method for a femtocell to reduce interference with an overlapping macrocell. The femtocell determines soft-frequency-reuse (“SFR”) information of the macrocell. From that information, the femtocell determines which frequency subchannels are assigned by the macrocell for its cell-center users and which frequency subchannels are assigned for cell-edge users. (Cell-edge users are given a higher transmission power profile in order to overcome potential interference with neighboring macrocells.) Then, the femtocell selects from the cell-center user frequency sub-channels for transmission to the femtocell'"'"'s users. By transmitting on the cell-center user frequency sub-channels, the femtocell reduces interference with the overlapping macro cell. The femtocell continues to update its knowledge of the macrocell'"'"'s SFR information and re-assigns frequency sub-channels as the SFR changes. If the macrocell detects that one of its cell-center users is “close enough” to the femtocell, then the macrocell re-assigns the cell-center user as a cell-edge user to overcome interference.

Claims

1. A method for a macrocell to reduce signal interference with a femtocell that overlaps the macrocell, the method comprising:

receiving, by the macrocell from a cell-center user of the macrocell, a neighbor list, the neighbor list comprising the femtocell and indicating that a strength of a signal received from the femtocell is above a threshold; and

scheduling, by the macrocell, in response to the strength of the signal received from the femtocell being above the threshold, the cell-center user to communicate via one or more frequency sub-channels included in a subset of a set of frequency sub-channels to be used by cell-center users of the macrocell, the frequency sub-channels in the subset being assigned higher power than the other frequency sub-channels in the set,

wherein a second set of frequency sub-channels is to be used by cell edge users of the macrocell.

2. The method according to claim 1, further comprising a step of assigning, by the macrocell, the set of frequency sub-channels to be used by cell-center users of the macrocell.

3. The method according to claim 1, further comprising a step of assigning, by the macrocell, the second set of frequency sub-channels to be used by cell-edge users of the macrocell.

4. A controller for controlling a macrocell, the controller comprising:

a transceiver; and

a processor operatively coupled to the transceiver and configured for receiving, via the transceiver from a cell-center user of the macrocell, a neighbor list, the neighbor list comprising a femtocell and indicating that a strength of a signal received from the femtocell is above a threshold, and for scheduling, in response to the strength of the signal received from the femtocell being above the threshold, the cell-center user to communicate via one or more frequency sub-channels included in a subset of a set of frequency sub-channels to be used by cell-center users of the macrocell, the frequency sub- channels in the subset being assigned higher power than the other frequency sub-channels in the set,

wherein a second set of frequency sub-channels is to be used by cell edge users of the macrocell.

5. The controller according to claim 4, wherein the processor is further configured for assigning the set of frequency sub-channels to be used by cell-center users of the macrocell.

6. The controller according to claim 4, wherein the processor is further configured for assigning a second set of frequency sub-channels to be used by cell-edge users of the macrocell.