Synchronous TDM-based communication in dominant interference scenarios

Patent metadata

Field	Value
Publication number	US-9485773-B2
Application number	US-201313888292-A
Country	US
Kind code	B2
Filing date	May 6, 2013
Priority date	Jul 11, 2008
Publication date	Nov 1, 2016
Grant date	Nov 1, 2016

Abstract

Techniques for supporting communication in a heterogeneous network are described. In an aspect, communication in a dominant interference scenario may be supported by reserving subframes for a weaker base station observing high interference from a strong interfering base station. In another aspect, interference due to a first reference signal from a first station (e.g., a base station) may be mitigated by canceling the interference at a second station (e.g., a UE) or by selecting different resources for sending a second reference signal by the second station (e.g., another base station) to avoid collision with the first reference signal. In yet another aspect, a relay may transmit in an MBSFN mode in subframes that it listens to a macro base station and in a regular mode in subframes that it transmits to UEs. In yet another aspect, a station may transmit more TDM control symbols than a dominant interferer.

First claim

What is claimed is:

1. A method for wireless communication, comprising:
identifying, at a second station, a first station causing high interference to the second station in a heterogeneous network comprising base stations of at least two different transmit power levels, wherein the first station is a base station or a relay station and the second station is a user equipment (UE); and
mitigating interference, at the second station, due to a first reference signal from the first station by canceling the interference due to the first reference signal at the UE;
wherein the canceling of the interference comprises:
estimating the interference due to the first reference signal at the UE,
subtracting the estimated interference from a signal received at the UE from a third station to obtain an interference-canceled signal, and
processing the interference-canceled signal to obtain a channel estimate for the third station.

2. The method of claim 1 , wherein the first station is a macro base station.

3. The method of claim 1 , wherein the first station is a femto base station.

4. A method for wireless communication, comprising:
identifying, at a second station, a first station causing high interference to the second station or observing high interference from the second station in a heterogeneous network comprising base stations of at least two different transmit power levels; and
mitigating interference, at the second station, associated with a first reference signal from the first station including mitigating interference to the first reference signal by clearing resources associated with the first reference signal and selecting different resources for sending a second reference signal by the second station to avoid collision with the first reference signal;
wherein the mitigating interference to the first reference signal comprises
determining first resources used to send the first reference signal by the first station,
selecting a cell identity (ID) associated with second resources for sending the second reference signal, the second resources being different from the first resources,
sending the second reference signal on the second resources by the second station,
generating a primary synchronization signal and a secondary synchronization signal based on the selected cell ID, and
sending the primary and secondary synchronization signals in designated subframes by the second station.

5. The method of claim 1 , wherein the first resources comprise a first set of subcarriers, and wherein the second resources comprise a second set of subcarriers different from the first set of subcarriers.

6. An apparatus for wireless communication, comprising:
means for identifying, at a second station, a first station causing high interference to the second station in a heterogeneous network comprising base stations of at least two different transmit power levels, wherein the first station is a base station or a relay station and the second station is a user equipment (UE); and
means for mitigating interference, at the second station, due to a first reference signal from the first station by canceling the interference due to the first reference signal at the UE;
wherein the canceling of the interference by the means for mitigating interference comprises:
estimating the interference due to the first reference signal at the UE,
subtracting the estimated interference from a signal received at the UE from a third station to obtain an interference-canceled signal, and
processing the interference-canceled signal to obtain a channel estimate for the third station.

7. An apparatus for wireless communication, comprising:
means for identifying, at a second station, a first station causing high interference to the second station or observing high interference from the second station in a heterogeneous network comprising base stations of at least two different transmit power levels; and
means for mitigating interference, at the second station, associated with a first reference signal from the first station by mitigating interference to the first reference signal by clearing resources associated with the first reference signal and selecting different resources for sending a second reference signal by the second station to avoid collision with the first reference signal;
wherein the means for—mitigating interference mitigates interference to the first reference signal by:
determining first resources used to send the first reference signal by the first station,
selecting a cell identity (ID) associated with second resources for sending the second reference signal, the second resources being different from the first resources,
sending the second reference signal on the second resources by the second station, and
generating a primary synchronization signal and a secondary synchronization signal based on the selected cell ID; and
sending the primary and secondary synchronization signals in designated subframes by the second station.

8. An apparatus for wireless communication, comprising:
a memory; and
at least one processor coupled to the memory and configured to:
identify, at a second station, a first station causing high interference to the second station in a heterogeneous network comprising base stations of at least two different transmit power levels, wherein the first station is a base station or a relay station and the second station is a user equipment (UE); and
mitigate interference, at the second station, due to a first reference signal from the first station by canceling the interference due to the first reference signal at the UE;
wherein the canceling of the interference comprises:
estimating the interference due to the first reference signal at the UE,
subtracting the estimated interference from a signal received at the UE from a third station to obtain an interference-canceled signal, and
processing the interference-canceled signal to obtain a channel estimate for the third station.

9. An apparatus for wireless communication, comprising:
a memory; and
at least one processor coupled to the memory and configured to:
identify, at a second station, a first station causing high interference to the second station or observing high interference from the second station in a heterogeneous network comprising base stations of at least two different transmit power levels; and
mitigate interference, at the second station, associated with a first reference signal from the first station, including mitigating interference to the first reference signal by clearing resources associated with the first reference signal and selecting different resources for sending a second reference signal by the second station to avoid collision with the first reference signal;
wherein mitigating interference to the first reference signal comprises
determining first resources used to send the first reference signal by the first station,
selecting a cell identity (ID) associated with second resources for sending the second reference signal, the second resources being different from the first resources, and to
sending the second reference signal on the second resources by the second station;
generating a primary synchronization signal and a secondary synchronization signal based on the selected cell ID, and
sending the primary and secondary synchronization signals in designated subframes by the second station.

10. A non-transitory computer-readable medium storing computer executable code for wireless communication, comprising code for causing at least one computer to:
identify, at a second station, a first station causing high interference to the second station in a heterogeneous network comprising base stations of

Assignees

• Qualcomm Inc

Inventors

• Bhattad Kapil
• Palanki Ravi

Classifications

• H04W72/541 Primary

  using the level of interference · CPC title

• H04J11/005 Primary

  of intercell interference · CPC title

• H04J11/0069 Primary

  Cell search, i.e. determining cell identity [cell-ID] (design of multiplexing codes H04J13/00; processing access restriction or access information H04W48/16; discovery of network devices for network data management H04W8/005; sounding signals for channel estimation H04L25/0226; structure of reference signals in multicarrier modulation systems H04L27/2613; frame, time or carrier synchronisation in multicarrier modulation systems H04L27/2655) · CPC title

• H04W16/32

  Hierarchical cell structures · CPC title

• H04J3/02

  Details (electronic switching or gating H03K17/00) · CPC title