FACILITATING INTERFERENCE MANAGEMENT IN MULTI-CELL AND MULTI-USER MILLIMETER WAVE CELLULAR NETWORKS

• US 20170311187A1
• Filed: 04/22/2016
• Published: 10/26/2017
• Est. Priority Date: 04/22/2016
• Status: Active Grant

• Current Assignee: City University of Hong Kong
• Original Assignee: City University of Hong Kong
• Inventors: DONG, MiaoMiao, CHAN, WaiMing, KIM, Taejoon
• Granted Patent: US 10,200,894 B2
• Time in Patent Office: Days
• CPC Class Codes: H04B 7/024 Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• CPC Class Codes: H04B 7/0408 using two or more beams, i.e. beam diversity
• CPC Class Codes: H04B 7/0695 using beam selection
• CPC Class Codes: H04B 7/0857 using maximum ratio combining techniques, e.g. signal-to- interference ratio [SIR], received signal strenght indication [RSS]
• CPC Class Codes: H04B 7/088 using beam selection
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic

Abstract

Interference management methods are proposed to facilitate multi-cell, multi-user millimeter wave cellular networks. One method includes a feedback approach in which a base station (BS) device collects information from mobile devices in the cell operated by the BS device and other BS devices in other cells. Each mobile device feeds back a best beams set and a worst interference beams set to its serving BS device and the information is shared amongst other BS devices in the network. According to the information, BS devices implement a beam selection criterion to select a beam for downlink transmission. To reduce feedback cost, another method leverages the channel reciprocity in time division duplexing to use the measured uplink power and interference information to select the narrow beam for downlink transmission. The BS device selects the narrow beam that establishes a reliable channel and reduces interference to mobile devices in neighboring cells.

Claims

1. A method, comprising:

receiving, by a base station device comprising a processor and associated with a cell, pilot signals transmitted from a mobile device using different precoders at different training slots in the cell associated with the base station device;

notifying, by the base station device, an index of a selected precoder of the different precoders used by the mobile device and that satisfies a defined condition;

transmitting, by the base station device, pilot signals to the mobile device, wherein the transmitting is performed using the different precoders at the different training slots;

collecting, by the base station device, feedback information from the mobile device, wherein the feedback information comprises;

a first information set determined based on received power detected at the mobile device and associated with the base station device at the different training slots; and

a second information set determined based on interference power detected at the mobile device from unassociated base station devices at the different training slots, wherein the unassociated base station devices are ones of the base station devices associated with different cells from the cell associated with the base station device, and wherein the unassociated base station devices and the base station device are included in a network;

sharing, by the base station device, information between other ones of the base station devices in the network to facilitate interference management;

partitioning, by the base station device, the first information set into a first group in which a beam does not contribute to interference for other mobile devices and a second group in which the beam does contribute to the interference for the other ones of the mobile devices, wherein the partitioning is based on third information received from the other base station devices;

determining, by the base station device, a first selected beam in the first group and determining a second selected beam in the second group; and

selecting, by the base station device, based on a criterion, the first selected beam in the first group or the second selected beam in the second group as a beam for the base station device to transmit a signal.

2. The method of claim 1, wherein the selecting the first selected beam or the second selected beam comprises:

selecting the second selected beam in the second group as the beam for the base station device to transmit the signal based on a determination that the first group includes no beams and the second group includes beams; and

selecting the first selected beam in the first group as the beam for base station device to transmit the signal based on a determination that the second group includes no beams and the first group includes beams.

3. The method of claim 2, wherein the selecting the beam for the base station device to transmit the signal further comprises:

selecting the first selected beam in the first group as the beam for the base station device to transmit the signal based on a determination that both the first group and the second group include beams and a received power of the first selected beam in the first group is greater than or equal to a defined value.

4. The method of claim 3, wherein the defined value is a difference between the received power of the second selected beam in the second group and a second power, and wherein the second power is computed as a product of a defined experience value and an interference power of the second selected beam in the second group.

5. The method of claim 2, wherein the selecting the beam for the base station device to transmit the signal further comprises:

selecting the second selected beam in the second group as the beam for the base station device based on a determination that both the first group and the second group include beams and a received power of first selected beam in the first group is less than a defined value.

6. The method of claim 5, wherein the defined value is a difference between the received power of the second selected beam in the second group and a second power, and wherein the second power is computed as a product of a defined experience value and an interference power of the second selected beam in the second group.

7. The method of claim 1, wherein the first selected beam in the first group does not contribute to interference for the other mobile devices and has a maximum received power among beams in the first group.

8. The method of claim 1, wherein the second selected beam in the second group contributes to interference for the other mobile devices and has a maximum received power-to-interference ratio among beams in the second group.

9. The method of claim 1, wherein the third information is indicative of the shared second information set in the network from another base station device other than the base station device.

10. The method of claim 9, further comprising:

determining, by the base station device, whether any beams in the first information set are reported as interfering beams in the second information set in the network.

11. The method of claim 10, wherein:

for a beam in the first information set that is reported as an interfering beam in the second information set in the network, determining a first overall interference that the beam in the first information set provides to other mobile devices; and

for another beam in the first information set that is not reported as an interfering beam in the second information set in the network, determining a second overall interference that the beam in the first beam set provides to other mobile devices as zero.

13. The method of claim 1, wherein the base station device collects the feedback information, the first information set and the second information set, from the mobile device.

14-1. The method of claim 13, wherein the selecting the beam for the base station device to transmit the signal comprises:

selecting the second selected beam in the second group as the beam for the base station device to transmit the signal based on a determination that the first group includes no beams and the second group includes beams, and selecting the first selected beam in the first group as the beam for base station device to transmit the signal based on a determination that the second group includes no beams and the first group includes beams.

19. The method of claim 13, wherein the first selected beam in the first group does not suffer interference from other mobile devices and has a maximum received power among beams in the first group.

20. The method of claim 13, wherein the second selected beam in the second group suffers interference from the other mobile devices and has a maximum received power-to-interference ratio among the beams in the second group.

21. The method of claim 13, wherein the base station device is a millimeter wave base station device configured to transmit the signal, and wherein the signal comprises control and data information.

22. The method of claim 13, further comprising:

determining, by the base station device, the first information set based on uplink received power from the mobile device at the different training slots and measuring uplink interference power that a beam in the first information set suffers from out-of-cell unassociated mobile devices; and

selecting, by the base station device, the beam for downlink transmission based on the uplink information in the first information by utilization of channel reciprocity in a time division duplex system.

12. The method of claim 12, wherein the base station device comprises a millimeter wave base station device.

14. A method, comprising:

transmitting, by a base station device comprising a processor and associated with a cell, to a mobile device, downlink information including pilot signals, wherein the transmitting is performed using fixed precoder at different training slots in a cell associated with the base station device;

receiving, by the base station device, using the different combiners at the different training slots, the pilot signals transmitted from the mobile device in the cell associated with the base station device;

determining, by the base station device, a first information set based on received power from the mobile device at the different training slots and measuring interference power that a beam in the first information set suffers from out-of-cell unassociated mobile devices at the different training slots;

partitioning, by the base station device, the first information set into a first group in which a first set of beams have no interference from the out-of-cell unassociated mobile devices and a second group in which a second set of beams have interference from the out-of-cell unassociated mobile devices;

determining, by the base station device, a first selected beam in the first group and determining a second selected beam in the second group; and

selecting, by the base station device, based on a criterion, the first selected beam in the first group or the second selected beam in the second group as the beam for the base station device to transmit a signal.

15. The method of claim 14, wherein the selecting the beam for the base station device to transmit the signal further comprises:

selecting the first selected beam in the first group as the beam for the base station device to transmit the signal based on a determination that both the first group and the second group include beams and a received power of the first selected beam in the first group is greater than or equal to a defined value.

16. The method of claim 15, wherein the defined value is a difference between the received power of the second selected beam in the second group and a second power, and wherein the second power is computed as a product of a defined experience value and an interference power of the second selected beam in the second group.

17. The method of claim 14, wherein the selecting the beam further comprises:

selecting the second selected beam in the second group as the beam for the base station device to transmit the signal based on a determination that both the first group and the second group include beams and the received power of the first selected beam in the first group is smaller than a defined value.

18. The method of claim 17, wherein the defined value is a difference between the power of the second selected beam in the second group and a second power, and wherein the second power is computed as a product of a defined experience value and the interference power of the second selected beam in the second group.

23. A computer-readable medium storing computer-executable instructions that, in response to execution, cause a processor to perform operations, comprising:

determining, by base station device comprising a processor, a first information set based on received power from mobile device at different training slots and measuring interference power that a beam in the first information set suffers from out-of-cell unassociated mobile devices at the different training slots;

partitioning, by the base station device, the first information set into a first group in which a first set of beams have no interference from other mobile devices and a second group in which a second set of beams have interference from other mobile devices;

determining, by the base station device, a first selected beam in the first group and determining a second selected beam in the second group; and

selecting, by the base station device, based on a criterion, the first selected beam in the first group or the second selected beam in the second group as the beam for the base station device to transmit a signal.

24. The computer-readable medium of claim 23, wherein the selecting the first selected beam or the second selected beam comprises:

selecting the second selected beam in the second group as the beam for the base station device to transmit the signal based on a determination that the first group includes no beams and the second group includes beams, and selecting the first selected beam in the first group as the beam for base station device to transmit the signal based on a determination that the second- group includes no beams and the first group includes beams.

25. The computer-readable medium of claim 24, wherein the selecting the beam for the base station device to transmit the signal further comprises:

selecting the first selected beam in the first group as the beam for the base station device to transmit the signal based on a determination that both the first group and the second group include beams and a received power of the first selected beam in the first group is greater than or equal to a defined value.

26. The computer-readable medium of claim 25, wherein the defined value is a difference between the received power of a second selected beam in the second group and a second power, and wherein the second power is computed as a product of a defined experience value and an interference power of the second selected beam in the second group.

27. The computer-readable medium of claim 24, wherein the selecting the beam for the base station device to transmit the signal further comprises:

selecting the second selected beam in the second group as the beam for the base station device based on a determination that both the first group and the second group include beams and a received power of first selected beam in the first group is less than a defined value.

28. The computer-readable medium of claim 27, wherein the defined value is a difference between the received power of the second selected beam in the second group and a second power, and wherein the second power is computed as a product of a defined experience value and an interference power of the second selected beam in the second group.