Selective interference cancellation in the range-expansion region of a heterogeneous network

1. A method of receiving a target link signal at a receiving device, wherein the target link signal is received in a received signal that also includes an interfering link signal, the method comprising:

determining that the receiving device is operating in a range-expansion region of a low-power node in a heterogeneous network deployment, based on a serving-cell geometry metric or a dominant-interferer ratio metric or both;

responsive to determining that the receiving device is operating in a range-expansion region, configuring the receiving device to perform interference cancellation, wherein said configuring is based on said determining;

performing said interference cancellation on the interfering link signal; and

demodulating and decoding the target link signal to provide a target link bit stream.

2. The method of claim 1 , wherein configuring the receiving device to perform interference cancellation comprises selecting one or more of a plurality of interference-cancellation techniques, wherein said selecting is based on determining that the receiving device is operating in the range-expansion region.

3. The method of claim 2 , wherein said selecting comprises selecting a post-decoding data-channel interference-cancellation technique in response to determining that the receiving device is operating in the range-expansion region.

4. The method of claim 3 , wherein said selecting further comprises selecting a non-data-channel interference-cancellation technique in response to determining that the receiving device is operating in the range-expansion region, and wherein performing said interference cancellation on the interfering link signal comprises performing both the post-decoding data-channel interference-cancellation technique and the non-data-channel interference-cancellation technique on the interfering link signal.

5. The method of claim 1 , wherein performing said interference cancellation on the interfering link signal comprises generating an interference-cancellation signal according to an interference-cancellation technique and incorporating information of the interference-cancellation signal in the received signal, and wherein demodulating and decoding the target link signal is responsive to said incorporating information of the interference-cancellation signal in the received signal.

6. The method of claim 1 , wherein configuring the receiving device to perform interference cancellation comprises configuring the receiver to receive relevant signals from the network, the relevant signals comprising one or more of signal format information for the interfering link signal, mobile terminal identifier information for the interfering link signal, and control signal contents for the interfering link signal; and wherein performing the interference cancellation comprises obtaining the relevant signals and using the relevant signals to perform interference cancellation on a per-transmit-time-interval basis.

7. The method of claim 6 , wherein at least a portion of the relevant signals are obtained via assistance information transmitted from an interfering cell.

8. The method of claim 6 , wherein at least a portion of the relevant signals are obtained via assistance information transmitted from a serving cell.

9. The method of claim 6 , wherein at least a portion of the relevant signals are obtained via blind decoding performed on an interfering channel signal.

10. The method of claim 1 , wherein determining that the receiving device is operating in the range-expansion region is based at least in part on evaluating a signal geometry for the target link signal and determining that the signal geometry for the target link signal is less than about −2 dB.

11. The method of claim 1 , wherein determining that the receiving device is operating in the range-expansion region is based at least in part on determining that the proportion of received interference power generated by a single interfering source exceeds a first predetermined threshold.

12. The method of claim 11 , wherein determining that the proportion of received interference power generated by a single interfering source exceeds a predetermined threshold comprises determining that

RSCP

1

∑

i

≠

1

⁢

RSCP

i

>

τ

1

,

where RSCP i is the received signal code power for cell i, i=1 for the single interfering source, i=0 for the target link signal, and τ 1 is the first predetermined threshold.

13. The method of claim 1 , wherein determining that the receiving device is operating in the range-expansion region is based at least in part on computing a ratio of the received signal code power (RSCP) for the interfering link signal to a scaled measure of the total received signal power and comparing the ratio to a second predetermined threshold.

14. The method of claim 13 , wherein determining that the receiving device is operating in the range-expansion region comprises determining that

RSCP

1

(

E

c

,

CPICH

I

or

)

⁢

RSSI

>

τ

2

,

where RSCP 1 is the received signal code power for the interfering link signal, RSSI is the total received power,

(

E

c

,

CPICH

I

or

)

is the fraction of transmitted base station power allocated to the common pilot channel, and τ 2 is the predetermined threshold.

15. A receiver device comprising a receiver circuit configured to receive a target link signal wherein the target link signal is received in a received signal also including an interfering link signal, and further comprising a controller circuit configured to:

control the receiver circuit to perform own-cell and other-cell measurements;

determine that the receiver device is operating in a range-expansion region of a low-power node in a heterogeneous network deployment, based on a serving-cell geometry metric or a dominant-interferer ratio metric or both;

responsive to determining that the receiver device is operating in a range-expansion region, configure the receiver circuit to perform interference cancellation, wherein said configuring is based on said determining; and

control the receiver circuit to perform said interference cancellation on the interfering link signal and to demodulate and decode the target link signal to provide a target link bit stream.

16. The receiver device of claim 15 , wherein the controller circuit is configured to configure the receiving circuit to perform interference cancellation by selecting one or more of a plurality of interference-cancellation techniques, wherein said selecting is based on determining that the receiver device is operating in the range-expansion region.

17. The receiver device of claim 16 , wherein said selecting comprises selecting a post-decoding data-channel interference-cancellation technique in response to determining that the receiver device is operating in the range-expansion region.

18. The receiver device of claim 17 , wherein said selecting further comprises selecting a non-data-channel interference-cancellation technique in response to determining that the receiver device is operating in the range-expansion region, and wherein the controller circuit is configured to control the receiver circuit to perform both the post-decoding data-channel interference-cancellation technique and the non-data-channel interference-cancellation technique on the interfering link signal.

19. The receiver device of claim 15 , wherein the receiver circuit is configured to perform said interference cancellation on the interfering link signal by generating an interference-cancellation signal according to an interference-cancellation technique and incorporating information of the interference-cancellation signal in the received signal, and to demodulate and decode the target link signal responsive to said incorporating information of the interference-cancellation signal in the received signal.

20. The receiver device of claim 15 , wherein the controller circuit is configured to configure the receiver circuit to perform interference cancellation by configuring the receiver circuit to receive relevant signals from the network, the relevant signals comprising one or more of signal format information for the interfering link signal, mobile terminal identifier information for the interfering link signal, and control signal contents for the interfering link signal; whereby the receiver circuit is configured to perform the interference cancellation by obtaining the relevant signals and using the relevant signals to perform interference cancellation on a per-transmit-time-interval basis.

21. The receiver device of claim 20 , wherein the controller circuit and receiver circuit are configured to obtain at least a portion of the relevant signals via assistance information transmitted from an interfering cell.

22. The receiver device of claim 20 , wherein the controller circuit and receiver circuit are configured to obtain at least a portion of the relevant signals via assistance information transmitted from a serving cell.

23. The receiver device of claim 20 , wherein the controller circuit and receiver circuit are configured to obtain at least a portion of the relevant signals via blind decoding performed on an interfering channel signal.

24. The receiver device of claim 15 , wherein the controller circuit is configured to determine that the receiver device is operating in the range-expansion region based at least in part on evaluating a signal geometry for the target link signal and determining that the signal geometry for the target link signal is less than about −2 dB.

25. The receiver device of claim 15 , wherein the controller circuit is configured to determine that the receiver device is operating in the range-expansion region based at least in part on determining that the proportion of received interference power generated by a single interfering source exceeds a first predetermined threshold.

26. The receiver device of claim 25 , wherein the controller circuit is configured to determine that the proportion of received interference power generated by a single interfering source exceeds a predetermined threshold by determining that

RSCP

1

∑

i

≠

1

⁢

RSCP

i

>

τ

1

,

where RSCP i is the received signal code power for cell i, i=1 for the single interfering source, i=0 for the target link signal, and τ 1 is the first predetermined threshold.

27. The receiver device of claim 25 , wherein the controller circuit is configured to determine that the receiver device is operating in the range-expansion region based at least in part on computing a ratio of the received signal code power (RSCP) for the interfering link signal to a scaled measure of the total received signal power and comparing the ratio to a second predetermined threshold.

28. The receiver device of claim 27 , wherein the controller circuit is configured to determine that the receiver device is operating in the range-expansion region by determining that

RSCP

1

(

E

c

,

CPICH

I

or

)

⁢

RSSI

>

τ

2

,

where RSCP 1 is the received signal code power for the interfering link signal, RSSI is the total received power,

(

E

c

,

CPICH

I

or

)

is the fraction of transmitted base station power allocated to the common pilot channel, and τ 2 is the predetermined threshold.

29. A mobile terminal comprising a receiver configured to receive a target link signal wherein the target link signal is received in a received signal that also includes an interfering link signal, and further comprising:

a controller configured to determine that the mobile terminal is operating in a range-expansion region of a low-power node in a heterogeneous network deployment, based on a serving-cell geometry metric or a dominant-interferer ratio metric or both;

a configuration module for configuring the receiver to perform interference cancellation, responsive to the controller's determining that the mobile terminal is operating in a range-expansion region;

wherein the receiver is arranged to perform said interference cancellation on the interfering link signal and to demodulate and decode the target link signal to provide a target link bit stream.

30. A non-transitory computer-readable medium comprising, stored thereupon, a computer program product for execution by a receiving device arranged to receive a target link signal, wherein the target link signal is received in a received signal that also includes an interfering link signal, the computer program product comprising program instructions for:

determining that the receiving device is operating in a range-expansion region of a low-power node in a heterogeneous network deployment, based on a serving-cell geometry metric or a dominant-interferer ratio metric or both;

responsive to determining that the receiving device is operating in a range-expansion region, configuring the receiving device to perform interference cancellation, wherein said configuring is based on said determining;

performing said interference cancellation on the interfering link signal; and

demodulating and decoding the target link signal to provide a target link bit stream.