METRIC COMPUTATION FOR INTERFERENCE-AWARE ROUTING

• US 20140086080A1
• Filed: 09/24/2013
• Published: 03/27/2014
• Est. Priority Date: 09/26/2012
• Status: Active Grant

• Current Assignee: Optis Cellular Technology LLC (Brevet Capital)
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Hui, Dennis, Balachandran, Kumar, Baldemair, Robert, Tullberg, Hugo, Axns, Johan
• Granted Patent: US 9,351,228 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04L 45/124 using a combination of metrics
• CPC Class Codes: H04W 40/16 based on interference
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Systems and methods for computing and/or utilizing mutual information based link metrics for a link in a wireless mesh network are disclosed. In one embodiment, one or more mutual information values are computed for a link between a transmitter of a first network node and a receiver of a second network node in a wireless mesh network. Each of the one or more mutual information values is computed for a different hypothesized transmission mode for the link. One or more link metrics for the link are computed as a function of the mutual information values, where each link metric is computed based on a different one of the one or more mutual information values. In this manner, a link metric is computed for each of the one or more hypothesized transmission modes for the link. At least one of the link metrics are then provided to a routing update module.

Claims

1. A method comprising:

computing one or more mutual information values for a link between a transmitter of a first network node and a receiver of a second network node in a wireless mesh network, wherein each of the one or more mutual information values comprises a mutual information value for the link for a different one of one or more transmission modes;

computing one or more link metrics for the link as a function of the one or more mutual information values, where each link metric of the one or more link metrics is a function of a different one of the one or more mutual information values; and

providing at least one of the one or more link metrics to a routing update module.

2. The method of claim 1 wherein computing the one or more mutual information values comprises, for each transmission mode of the one or more transmission modes:

computing a signal-to-interference-plus-noise ratio for the link for the transmission mode; and

computing the mutual information value for the link for the transmission mode as a function of the signal-to-interference-plus-noise ratio.

3. The method of claim 1 wherein the one or more transmission modes comprise a plurality of hypothesized transmission modes, and each hypothesized transmission mode corresponds to a different combination of transmission configuration parameters for the transmitter of the first network node and transmitters of one or more neighboring network nodes in the wireless mesh network that potentially cause interference to the link between the transmitter of the first network node and the receiver of the second network node.

4. The method of claim 3 wherein computing the one or more mutual information values comprises, for each hypothesized transmission mode of the plurality of hypothesized transmission modes:

computing a signal-to-interference-plus-noise ratio for the link for the hypothesized transmission mode; and

computing the mutual information value for the link for the hypothesized transmission mode as a function of the signal-to-interference-plus-noise ratio.

5. The method of claim 4 wherein, for each hypothesized transmission mode of the plurality of hypothesized transmission modes, computing the mutual information value for the link for the hypothesized transmission mode as a function of the signal-to-interference-plus-noise ratio comprises computing the mutual information value as a logarithm of an affine function of the signal-to-interference-plus-noise ratio for the link for the hypothesized transmission mode.

6. The method of claim 4 wherein, for each hypothesized transmission mode of the plurality of hypothesized transmission modes, computing the mutual information value for the link for the hypothesized transmission mode as a function of the signal-to-interference-plus-noise ratio comprises computing the mutual information value as:

I(l,m)=log₂(1+SINR(l,m))≡

D₁(SINR(l,m))

where I(l,m) is the mutual information value for the link l for the hypothesized transmission mode m and SINR(l,m) is the signal-to-interference-plus-noise ratio for the link l for the hypothesized transmission mode m.

7. The method of claim 6 wherein the transmitter of the first network node has a single antenna.

8. The method of claim 7 wherein, for each hypothesized transmission mode of the plurality of hypothesized transmission modes, computing the signal-to-interference-plus-noise ratio for the link for the hypothesized transmission mode comprises computing the signal-to-interference-plus-noise ratio for the link for the hypothesized transmission mode based on the equation:

9. The method of claim 6 wherein the transmitter of the first network node has multiple antennas and transmits a single stream.

10. The method of claim 9 wherein, for each hypothesized transmission mode of the plurality of hypothesized transmission modes, computing the signal-to-interference-plus-noise ratio for the link for the hypothesized transmission mode comprises computing the signal-to-interference-plus-noise ratio for the link for the hypothesized transmission mode based on the equation:

SINR(l,m)≡

p^H_l,mH^H_lQ<sup>−

1</sup>_l,mH_lp_l,m

where p_l,m is a precoding vector defined as;

p_l,m=(p⁽¹⁾_l,m, p⁽²⁾_l,m, . . . , p^(nT,l)_l,m)^T

whose elements specify an antenna weight assigned to the multiple n_T,l antennas of the transmitter of the first network node for the link l for the hypothesized transmission mode m, H_l is a n_R,l-by-n_T,l channel response matrix whose elements specify a complex-valued channel gain from each of the multiple antennas of the transmitter of the first network node to each of a number n_R,l of receive antennas of the receiver of the second network node for the link l,

Q_l,m≡

Q_noise+Σ

H_l′

p<sub>l′

,m</sub>p^H<sub>l′

,m</sub>H^H_l′

is a noise-plus-interference covariance matrix, and Q_noise is a covariance matrix of noise.

11. The method of claim 3 wherein the transmitter of the first network node has multiple antennas and transmits multiple streams.

12. The method of claim 11 wherein computing the one or more mutual information values comprises, for each hypothesized transmission mode of the plurality of hypothesized transmission modes:

computing a per-stream signal-to-interference-plus-noise ratio for the link for the hypothesized transmission mode for each stream of the multiple streams; and

computing the mutual information value for the link for the hypothesized transmission mode as a function of the per-stream signal-to-interference-plus-noise ratios for the multiple streams.

13. The method of claim 12 wherein, for each hypothesized transmission mode of the plurality of hypothesized transmission modes, computing the mutual information value for the link for the hypothesized transmission mode as a function of the per-stream signal-to-interference-plus-noise ratios for the multiple streams comprises computing the mutual information value as:

14. The method of claim 13 wherein, for each of the multiple streams, the receiver of the second network node is enabled to successively cancel interference caused by other streams, and the per-stream signal-to-interference-plus-noise ratio for the i-th stream of the multiple streams for the link l for the hypothesized transmission mode m is defined as:

SINR⁽ⁱ⁾(l, m)≡

p^H_l,m,iH^H_lQ<sup>−

1</sup>_l,m,iH_lp_l,m,i

where

15. The method of claim 13 wherein the receiver of the second network node is not enabled to perform successive interference cancellation for the multiple streams, and the per-stream signal-to-interference-plus-noise ratio for the i-th stream of the multiple streams for the link l for the hypothesized transmission mode m is defined as:

SINR⁽ⁱ⁾(l,m)≡

p^H_l,m,iH^H_lQ<sup>−

1</sup>_l,m,iH_lp_l,m,i

where

16. The method of claim 1 wherein the link is provided according to a multi-subcarrier wireless communication scheme, and computing the one or more mutual information values comprises, for each transmission mode of the one or more transmission modes, computing the mutual information value for the link for the transmission mode as a function of instantaneous mutual information values of individual subcarriers for the link for the transmission mode over multiple subcarriers.

17. The method of claim 1 wherein computing the one or more mutual information values comprises, for each transmission mode of the one or more transmission modes, computing the mutual information value for the link for the transmission mode as a function of instantaneous mutual information values of individual time slots for the link for the transmission mode over multiple time slots.

18. The method of claim 1 wherein computing the one or more mutual information values comprises computing the one or more mutual information values at the second network node.

19. The method of claim 18 wherein providing the at least one of the one or more link metrics to the routing update module comprises providing the at least one of the one or more link metrics to the routing update module at the first network node.

20. The method of claim 18 wherein the routing update module is a centralized routing update module at a centralized node associated with the wireless mesh network, and providing the at least one of the one or more link metrics to the routing update module comprises providing the at least one of the one or more link metrics to the routing update module at the centralized node.

21. The method of claim 1 wherein computing the one or more mutual information values comprises computing the one or more mutual information values at a centralized link metric computing module at a centralized node associated with the wireless mesh network.

22. The method of claim 1 further comprising:

computing, by the routing update module, one or more routing metrics for one or more potential routes through the wireless mesh network comprising the link between the transmitter of the first network node and the receiver of the second network node based on the at least one of the one or more link metrics for the link between the transmitter of the first network node and the receiver of the second network node; and

updating a routing table for the transmitter of the first network node based on the one or more routing metrics.

23. The method of claim 22 wherein the routing update module is at the first network node.

24. The method of claim 22 wherein the routing update module is a centralized routing update module at a centralized node associated with the wireless mesh network, and the method further comprises providing the routing table from the centralized node to the first network node.

25. The method of claim 1 wherein the wireless mesh network is a wireless mesh backhaul network for a plurality of wireless access nodes, including the first network node and the second network node, for a cellular communications network.

26. A method comprising:

obtaining one or more mutual information based link metrics for a link between a transmitter of a first network node and a receiver of a second network node in a wireless mesh network, wherein each of the one or more mutual information based link metrics comprises a mutual information based link metric for the link for a different one of one or more transmission modes;

computing one or more routing metrics for one or more potential routes through the wireless mesh network comprising the link between the transmitter of the first network node and the receiver of the second network node based on the one or more mutual information based link metrics for the link between the transmitter of the first network node and the receiver of the second network node; and

updating a routing table for the transmitter of the first network node based on the one or more routing metrics.

27. A method comprising:

for each link of a plurality of links between transmitters and receivers of at least a subset of a plurality of network nodes in a wireless mesh network, obtaining one or more mutual information based link metrics for the link, wherein each of the one or more mutual information based link metrics comprises a mutual information based link metric for the link for a different one of one or more transmission modes for the link;

computing a plurality of routing metrics for a plurality of potential routes through the wireless mesh network from a first network node to a second network node as a function of the one or more mutual information based link metrics for ones of the plurality of links included in the plurality of potential routes;

selecting one of the plurality of potential routes having a best routing metric from the plurality of routing metrics as a best route from the first network node to the second network node; and

updating a routing table to reflect the best route from the first network node to the second network node.

28. The method of claim 27 wherein the best route is also indicative of a best transmission mode for each link from the plurality of links that is included in the best route.

29. A node associated with a wireless mesh network comprising:

at least one of a radio subsystem and a network interface; and

a processing subsystem connected to the at least one of the radio subsystem and the network interface and configured to;

compute one or more mutual information values for a link between a transmitter of a first network node and a receiver of a second network node in the wireless mesh network, wherein each of the one or more mutual information values comprises a mutual information value for the link for a different one of one or more transmission modes;

compute one or more link metrics for the link as a function of the one or more mutual information values, where each link metric of the one or more link metrics is a function of a different one of the one or more mutual information values; and

provide at least one of the one or more link metrics to a routing update module.

30. The node of claim 29 wherein the node is the second network node.

31. The node of claim 29 wherein the node is a central node that provides a centralized link metric computing function for the wireless mesh network.

32. A node associated with a wireless mesh network comprising:

at least one of a radio subsystem and a network interface; and

a processing subsystem connected to the at least one of the radio subsystem and the network interface and configured to;

obtain one or more mutual information based link metrics for a link between a transmitter of a first network node and a receiver of a second network node in the wireless mesh network, wherein each of the one or more mutual information based link metrics comprises a mutual information based link metric for the link for a different one of one or more transmission modes;

compute one or more routing metrics for one or more potential routes through the wireless mesh network comprising the link between the transmitter of the first network node and the receiver of the second network node based on the one or more mutual information based link metrics for the link between the transmitter of the first network node and the receiver of the second network node; and

update a routing table for the transmitter of the first network node based on the one or more routing metrics.

33. The node of claim 32 wherein the node is the first network node.

34. The node of claim 32 wherein the node is a central node that provides a centralized route updating function for the wireless mesh network.