ENABLING COEXISTENCE BETWEEN FDD AND TDD WIRELESS NETWORKS

• US 20120082038A1
• Filed: 10/01/2010
• Published: 04/05/2012
• Est. Priority Date: 10/01/2010
• Status: Active Grant

• Current Assignee: Clearwire Ip Holdings LLC (Deutsche Telekom AG)
• Original Assignee: Clear Wireless LLC (Deutsche Telekom AG)
• Inventors: XU, Yang, HART, Michael, GELBMAN, Peter, SAVA, Herkole
• Granted Patent: US 8,681,660 B2
• Time in Patent Office: Days
• US Class Current: 370/244
• CPC Class Codes: H04J 11/0023 Interference mitigation or co-ordination direct sequence spread spectrum [DSSS] systems H04B1/7097; frequency hopping H04B1/713; allocation criteria for ingress interference avoidance H04L5/0062; frequency allocation criteria for requirements on out-of-channel emissions H04L5/0066; arrangements for removing intersymbol interference or baseband equalisers H04L25/03006; peak power aspects in multicarrier modulation H04L27/2614; power management H04W52/00; traffic scheduling H04W72/54, H04W72/541
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 5/0044 allocation of payload
• CPC Class Codes: H04L 5/0062 Avoidance of ingress interference, e.g. ham radio channels
• CPC Class Codes: H04W 56/00 Synchronisation arrangements
• CPC Class Codes: H04W 72/20 Control channels or signalling for resource management
• CPC Class Codes: H04W 72/541 using the level of interference
• CPC Class Codes: H04W 72/542 using measured or perceived quality

Abstract

Systems and methods for detecting and mitigating interference between from a wireless time division duplex (TDD) communications device and a wireless frequency division duplex (FDD) communications device includes processing quality-indicator reports received from the FDD device to determine if the FDD device has experienced interference from the TDD device. Such interference may be mitigated by adjusting a downlink configuration of the FDD base station in communication with the FDD device. To detect and mitigate interference from an FDD device to a TDD device, it is determined if a monitored value of an operational parameter of the FDD device is within a fixed range of a maximum value of the operational parameter, and if so, a specific time interval or frequency of the FDD device is assigned for communication purposes. Similar interference detection and mitigation techniques may also be used for interference scenarios between two TDD systems including TDD devices.

Claims

1. A method of detecting and mitigating interference between a wireless time division duplex (TDD) communications device operational with a TDD base station and a wireless frequency division duplex (FDD) communications device, the method comprising:

processing, using a processor operatively associated with an FDD base station, quality-indicator reports received from the FDD device indicating a reception quality of one or more FDD data packets at the FDD device, wherein the processing indicates if the reception at the FDD device has experienced interference from the TDD device; and

responsive to a determination that the reception at the FDD device has experienced interference from the TDD device, adjusting, using the processor, a downlink configuration of the FDD base station to mitigate interference from the TDD device.

2. The method of claim 1, wherein the TDD base station comprises a WiMAX base station and the TDD device comprises a WiMAX device.

3. The method of claim 1, wherein the TDD base station comprises an LTE base station and the TDD device comprises an LTE device.

4. The method of claim 1, wherein the FDD base station comprises an LTE base station and the FDD device comprises an LTE device.

5. The method of claim 1, wherein said processing the quality-indicator reports is executed responsive to a determination that a transmission power of the FDD device is greater than a selectable transmission power threshold.

6. The method of claim 1, wherein said processing the quality-indicator reports is executed responsive to a determination that a triggering event has occurred.

7. The method of claim 5, wherein the triggering event comprises a service disruption event occurring between the FDD device and the FDD base station.

8. The method of claim 1, wherein said processing the quality-indicator reports includes determining whether the reception quality at the FDD device has met an acceptable-interference criterion.

9. The method of claim 8, further comprising determining an interference-free time interval based on a frame configuration of TDD frames, wherein said adjusting the downlink configuration is based on the interference-free time interval.

10. The method of claim 8, wherein said processing the quality-indicator reports is executed responsive to a determination that a rate of transmission of FDD data packets from the FDD base station to the FDD device is less than a load threshold.

11. The method of claim 10, wherein the load threshold is determined based on a rate of transmission of TDD data packets from the TDD base station to the TDD device.

12. The method of claim 10, wherein the load threshold is further determined based on a ratio of downlink time interval and uplink time interval, wherein the downlink and uplink time intervals are associated with the frame configuration of TDD frames.

13. The method of claim 1, further comprising periodically receiving the quality-indicator reports from the FDD device, wherein a period of receiving the quality-indicator reports is selectable, and

wherein said processing the quality-indicator reports comprises determining an actual quality-indicator report pattern for a set of periodically-received quality-indicator reports, the actual quality-indicator report pattern indicating if the reception at the FDD device has experienced interference from the TDD device.

14. The method of claim 13, wherein said processing the quality-indicator reports further comprises determining an interference-free time interval, wherein said adjusting the downlink configuration is based on the interference-free time interval.

15. The method of claim 13, wherein said periodically receiving the quality-indicator reports is executed responsive to a determination that a rate of transmission of FDD data packets from the FDD base station to the FDD device is greater than a load threshold.

16. The method of claim 13, further comprising:

determining, using the processor, an expected quality-indicator report pattern based on a frame configuration of TDD frames; and

correlating, using the processor, the actual quality-indicator report pattern with the expected quality-indicator report pattern to determine if the reception at the FDD device has experienced interference from the TDD device.

17. The method of claim 16, wherein said correlating comprises:

calculating a correlation value representing a correlation between the expected quality-indicator report pattern and the actual quality-indicator report pattern; and

comparing the calculated correlation value with a predetermined threshold value to determine if the reception at the FDD device has experienced interference from the TDD device.

18. The method of claim 16, further comprising:

synchronizing, using the processor, a frame start timing of a FDD frame with a frame start timing of a TDD frame based on a common time reference source, such that the start of a transmission of the FDD frame is aligned with the start of a transmission of the TDD frame,

wherein the expected quality-indicator report pattern is further based on the synchronized frame start timings of the FDD and TDD frames.

19. The method of claim 18, wherein the common time reference source comprises a Global Positioning System (GPS) or a device configured to operate in accordance with the IEEE 1588 standard.

20. The method of claim 1, wherein at least one of the quality-indicator reports includes an acknowledgement (ACK) signal or a non-acknowledgement (NACK) signal.

21. The method of claim 1, wherein at least one of the quality-indicator reports includes one or more channel quality indicator (CQI) values.

22. The method of claim 21, wherein the one or more CQI values include periodic CQI values received from the FDD device, wherein a period of the CQI values is selectable.

23. The method of claim 21, wherein the one or more CQI values include periodic CQI values received from the FDD device, wherein a period of the CQI values is predetermined in accordance with a frame configuration of TDD frames.

24. The method of claim 21, wherein the one or more CQI values are represented in a binary format.

25. The method of claim 1, wherein said adjusting the downlink configuration of the FDD base station comprises configuring the FDD base station, responsive to a determination that a data-quality requirement of the FDD device has not been met, such that the FDD base station transmits FDD data packets to the FDD device on a reduced-interference frequency selected from within an FDD downlink frequency band.

26. The method of claim 25, wherein the FDD downlink frequency band includes first and second frequencies, such that the first frequency is adjacent to a TDD transmission frequency band, and wherein the reduced-interference frequency is closer to the second frequency than the first frequency.

27. The method of claim 25, wherein the data-quality requirement of the FDD device comprises a Quality of Service (QoS) requirement for a particular application type.

28. The method of claim of 27, wherein the particular application type is a delay-constrained application.

29. The method of claim 27, wherein the particular application type is an application having a minimum data rate requirement.

30. The method of claim 27, wherein the particular application type is an application having a minimum jitter requirement.

31. The method of claim 1, wherein said adjusting the downlink configuration of the FDD base station comprises configuring the FDD base station such that the FDD base station transmits FDD data packets to the FDD device during an interference-free time interval.

32. A method of detecting and mitigating interference between a wireless frequency division duplex (FDD) communications device in communication with an FDD base station and a wireless time division duplex (TDD) communications device, wherein an FDD uplink frequency band includes first and second frequencies, such that the first frequency is adjacent to a TDD transmission frequency band, the method comprising:

determining, using a processor, whether a monitored value of an operational parameter of the FDD device is within a fixed range of a maximum value of the operational parameter; and

responsive to a determination that the monitored value of the operational parameter of the FDD device is within the fixed range of the maximum value of the operational parameter, performing at least one of;

configuring the FDD base station such that the FDD base station receives data packets from the FDD device on a reduced-interference frequency selected from within the FDD uplink frequency band such that the reduced-interference frequency is either closer to the second frequency than the first frequency, or the reduced-interference frequency is at a center of the FDD uplink frequency band, or

configuring the FDD base station such that the FDD device does not transmit data packets to the FDD base station during a TDD downlink time interval.

33. The method of claim 32, wherein a TDD base station in communication with the TDD base station comprises a WiMAX base station and the TDD device comprises a WiMAX device, and the FDD base station comprises an LTE base station and the FDD device comprises an LTE device.

34. The method of claim 32, wherein the operational parameter comprises a transmit power level at which the FDD device is transmitting FDD frames to the FDD base station.

35. The method of claim 32, further comprising providing a frame-structure parameter to the FDD base station, wherein the frame-structure parameter indicates a frame configuration of TDD frames including the TDD downlink time interval.

36. An apparatus capable of operating in a wireless network, and detecting and mitigating interference between wireless devices, the apparatus comprising:

a transceiver configured to exchange FDD data packets with a wireless frequency division duplex (FDD) communications device;

a memory device configured to store quality-indicator reports indicating a reception quality of one or more FDD data packets received at the FDD device;

a channel-quality module to process the quality-indicator reports for determining if the FDD device has experienced interference from a TDD device; and

a configuration-adjustment module to adjust a downlink configuration of the transceiver to mitigate interference from the TDD device, responsive to a determination that the FDD device has experienced interference from the TDD device.

37. The apparatus of claim 36, wherein the channel-quality module processes the quality-indicator reports responsive to a determination that a transmission power of the FDD device is greater than a selectable transmission power threshold.

38. The apparatus of claim 36, wherein the channel-quality module processes the quality-indicator reports responsive to a determination that a triggering event has occurred.

39. The apparatus of claim 38, wherein the triggering event comprises a service disruption event occurring between the transceiver and the FDD device.

40. The apparatus of claim 36, wherein the channel-quality module processes the quality-indicator reports by at least determining whether the reception quality at the FDD device has met an acceptable-interference criterion.

41. The apparatus of claim 40, further comprising a clean-slot module to determine an interference-free time interval based on a frame configuration of TDD frames, wherein the configuration-adjustment module adjusts the downlink configuration based on the interference-free time interval.

42. The apparatus of claim 40, wherein the channel-quality module processes the quality-indicator reports based on a determination that a rate of transmission of FDD data packets from the FDD base station to the FDD device is less than a load threshold.

43. The apparatus of claim 42, wherein the load threshold is determined based on a rate of transmission of TDD data packets from a TDD base station to the TDD device.

44. The apparatus of claim 42, wherein the load threshold is further determined based on a ratio of downlink time interval and uplink time interval, wherein the downlink and uplink time intervals are associated with the frame configuration of TDD frames.

45. The apparatus of claim 36, wherein the memory is configured to periodically receive the quality-indicator reports from the FDD device, such that a period of receiving the quality-indicator reports is selectable, and wherein the channel-quality module processes a set of periodically-received quality-indicator reports;

the apparatus further comprising;

a pattern-analysis module to determine an actual quality-indicator report pattern for the processed set of periodically-received quality-indicator reports, the actual quality-indicator report pattern indicating if the reception at the FDD device has experienced interference from the TDD device.

46. The apparatus of claim 45, further comprising a clean-slot module to determine an interference-free time interval, such that the configuration-adjustment module adjusts the downlink configuration based on the interference-free time interval.

47. The apparatus of claim 45, wherein the memory periodically receives the quality-indicator reports responsive to a determination that a rate of transmission of FDD data packets from the FDD base station to the FDD device is greater than a load threshold.

48. The apparatus of claim 45, wherein the pattern-analysis module is further configured to determine an expected quality-indicator report pattern of the FDD device based on a frame configuration of TDD frames;

the apparatus further comprising;

a correlation module to correlate the actual quality-indicator report pattern with the expected quality-indicator report pattern to determine if the FDD device has experienced interference from the TDD device.

49. The apparatus of claim 48, wherein the correlation module is configured to:

calculate a correlation value representing a correlation between the expected quality-indicator report pattern and the actual quality-indicator report pattern; and

compare the calculated correlation value with a predetermined threshold value to determine if the reception at the FDD device has experienced interference from the TDD device.

50. The apparatus of claim 48, further comprising:

a synchronization module to synchronize a frame start timing of a FDD frame with a frame start timing of a TDD frame based on a common time reference source, such that the start of a transmission of the FDD frame is aligned with the start of a transmission of the TDD frame,

wherein the expected quality-indicator report pattern is further based on the synchronized frame start timings of the FDD and TDD frames.

51. The apparatus of claim 50, wherein the common time reference source comprises a Global Positioning System (GPS) or a device configured to operate in accordance with the IEEE 1588 standard.

52. The apparatus of claim 36, wherein at least one of the quality-indicator reports includes an acknowledgement (ACK) signal or a non-acknowledgement (NACK) signal.

53. The apparatus of claim 36, wherein at least one of the quality-indicator reports includes one or more channel quality indicator (CQI) values.

54. The apparatus of claim 53, wherein the one or more CQI values include periodic CQI values received from the FDD device, wherein a period of the CQI values is selectable.

55. The apparatus of claim 53, wherein the one or more CQI values include periodic CQI values received from the FDD device, wherein a period of the CQI values is predetermined in accordance with a frame configuration of TDD frames.

56. The apparatus of claim 53, wherein the one or more CQI values are represented in a binary format.

57. The apparatus of claim 36, wherein the configuration-adjustment module to adjust the downlink configuration of the transceiver at least configures the transceiver, responsive to a determination that a data-quality requirement of the FDD device has not been met, such that the transceiver transmits FDD data packets to the FDD device on a reduced-interference frequency selected from within an FDD downlink frequency band.

58. The apparatus of claim 57, wherein the FDD downlink frequency band includes first and second frequencies, such that the first frequency is adjacent to a TDD transmission frequency band, and wherein the reduced-interference frequency is closer to the second frequency than the first frequency.

59. The apparatus of claim 57, wherein the data-quality requirement of the FDD device comprises a Quality of Service (QoS) requirement for a particular application type.

60. The apparatus of claim 57, wherein the particular application type is a delay-constrained application.

61. The apparatus of claim 57, wherein the particular application type is an application having a minimum data rate requirement.

62. The apparatus of claim 57, wherein the particular application type is an application having a minimum jitter requirement.

63. The apparatus of claim 36, wherein the configuration-adjustment module to adjust the downlink configuration of the transceiver at least configures the transceiver such that the transceiver transmits FDD data packets to the FDD device during an interference-free time interval.

64. An apparatus capable of operating in a wireless network, and detecting and mitigating interference between wireless devices, the apparatus comprising:

a transceiver configured to exchange FDD data packets with a wireless frequency division duplex (FDD) communications device, such that an FDD uplink frequency band includes first and second frequencies, such that the first frequency is adjacent to a TDD transmission frequency band of a TDD network;

a parameter-monitoring module to determine if a monitored value of an operational parameter of the FDD device is within a fixed range of a maximum value of the operational parameter;

a memory device configured to store the monitored value of the operational parameter of the FDD device, and frame information including a TDD downlink time interval associated with TDD frames; and

a configuration-adjustment module that, responsive to a determination that the monitored value is within the fixed range of the maximum value of the operational parameter, configures the transceiver such that;

the transceiver receives FDD data packets from the FDD device on a reduced-interference frequency selected from within the FDD uplink frequency band such that the reduced-interference frequency is either closer to the second frequency than the first frequency, or the reduced-interference frequency is at a center of the FDD uplink frequency band, or

the FDD device does not transmit data packets to the transceiver during the TDD downlink time interval.

65. The apparatus of claim 64, wherein the operational parameter comprises a transmit power level at which the FDD device is transmitting FDD frames to the transceiver.

66. A method of detecting and mitigating interference between a first wireless time division duplex (TDD) communications device operational with a first TDD base station and a second TDD device operational with a second TDD base station, the method comprising:

processing, using a processor operatively associated with the second TDD base station, quality-indicator reports received from the second TDD device indicating a reception quality of one or more TDD data packets at the second TDD device, wherein the processing indicates if the reception at the second TDD device has experienced interference from the first TDD device; and

responsive to a determination that the reception at the second TDD device has experienced interference from the first TDD device, adjusting, using the processor, a downlink configuration of the second TDD base station to mitigate interference from the first TDD device.

67. The method of claim 66, wherein at least one of the first TDD base station or the second TDD base station comprises a WiMAX base station, and at least one of the first TDD device or the second TDD device comprises a WiMAX device.

68. The method of claim 66, wherein at least one of the first TDD base station or the second TDD base station comprises an LTE base station, and at least one of the first TDD device or the second TDD device comprises an LTE device.

69. A method of detecting and mitigating interference between a first wireless frequency division duplex (TDD) communications device in communication with a first TDD base station and a second TDD device in communication with a second TDD base station, wherein a first TDD frequency band associated with the first TDD base station includes first and second frequencies, such that the first frequency is adjacent to a second TDD frequency band associated with the second TDD base station, the method comprising:

determining, using a processor, whether a monitored value of an operational parameter of the first TDD device is within a fixed range of a maximum value of the operational parameter; and

responsive to a determination that the monitored value of the operational parameter of the first TDD device is within the fixed range of the maximum value of the operational parameter, performing at least one of;

configuring the first TDD base station such that the first TDD base station receives data packets from the first TDD device on a reduced-interference frequency selected from within the first TDD frequency band, wherein the reduced-interference frequency is either closer to the second frequency than the first frequency, or the reduced-interference frequency is at a center of the first TDD frequency band, or

configuring the first TDD base station such that the first TDD device does not transmit data packets to the first TDD base station during a TDD downlink time interval associated with a frame configuration of the second TDD base station.