阅读说明：本技术 信道拥塞测量 (Channel congestion measurement ) 是由 P·S·德奥古恩 K·巴塔德 O·厄兹蒂尔克 张晓霞 J·孙 A·N·迪亚加拉詹 于 2020-03-13 设计创作，主要内容包括：本公开内容提供了用于基于话前侦听(LBT)失败的信道拥塞测量和恢复触发的系统、方法和装置。在一个方面中,用户设备(UE)可以基于尝试结合LBT过程执行上行链路传输的结果来确定LBT度量。例如,UE可以确定LBT失败的绝对数量、不成功上行链路传输与总上行链路传输尝试的比率、LBT成功的绝对数量或另一种类型的LBT度量。UE可以基于确定LBT度量满足门限来触发恢复动作,诸如无线电链路故障(RLF)恢复动作或带宽部分切换。(The present disclosure provides systems, methods, and apparatuses for channel congestion measurement and recovery triggering based on listen-before-talk (LBT) failures. In an aspect, a User Equipment (UE) may determine an LBT metric based on a result of attempting to perform an uplink transmission in conjunction with an LBT procedure. For example, the UE may determine an absolute number of LBT failures, a ratio of unsuccessful uplink transmissions to total uplink transmission attempts, an absolute number of LBT successes, or another type of LBT metric. The UE may trigger a recovery action, such as a Radio Link Failure (RLF) recovery action or a bandwidth partial handover, based on determining that the LBT metric satisfies the threshold.)

1. A method of wireless communication performed by an apparatus of a User Equipment (UE), comprising:

performing a set of Listen Before Talk (LBT) procedures to access an unlicensed spectrum;

determining an LBT metric associated with an outcome of the set of LBT procedures; and

selectively triggering a recovery procedure based on the LBT metric satisfying an LBT metric threshold.

2. The method of claim 1, wherein the LBT metric relates to a secondary cell, and wherein selectively triggering the recovery procedure comprises:

sending a report indicating that the LBT metric satisfies the LBT metric threshold for the secondary cell.

3. The method of claim 2, wherein the report includes information identifying at least one of:

the LBT metric,

A measurement report for the secondary cell,

A Channel Occupancy Time (COT) metric, or

A Received Signal Strength Indicator (RSSI) for the secondary cell.

4. The method of claim 1, wherein the LBT metric is at least one of:

a metric related to the number of LBT failures,

A metric related to a channel busy status as a result of an LBT failure, or

A metric related to the amount of data lost as a result of LBT failure.

5. The method of claim 1, wherein the LBT metric relates to a first bandwidth portion, and wherein selectively triggering the recovery procedure comprises:

performing a bandwidth portion switch from the first bandwidth portion to a second bandwidth portion.

6. The method of claim 5, wherein the second bandwidth portion is different from an initial access bandwidth portion or a default bandwidth portion.

7. The method of claim 5, further comprising:

sending a report message to a serving cell indicating that the bandwidth part handover is triggered,

wherein the report message is at least one of: a Radio Resource Control (RRC) message, a Medium Access Control (MAC) message, or a physical layer message.

8. The method of claim 7, wherein the report message includes information identifying at least one of:

bandwidth part switching trigger event, or

Number of LBT failures.

9. The method of claim 5, further comprising:

sending a report message to a serving cell after the bandwidth part switching,

wherein the report message is a Random Access Channel (RACH) message.

10. The method of claim 1, wherein selectively triggering the recovery procedure comprises at least one of:

triggering one or more Radio Link Failure (RLF) related procedures,

perform a recovery action, or

Reporting the LBT metric to a Base Station (BS).

11. The method of claim 1, wherein the LBT metric is an LBT failure metric.

12. The method of claim 11, wherein determining the LBT metric comprises:

determining that an LBT failure occurred for an LBT procedure of the set of LBT procedures based on a failure with respect to transmitting on an uplink transmission instance.

13. The method of claim 12, wherein the uplink transmission instance is at least one of:

physical Uplink Shared Channel (PUSCH) transmission,

Physical Uplink Control Channel (PUCCH) transmission, or

Physical Random Access Channel (PRACH) transmission, or

Sounding Reference Signal (SRS) transmission.

14. The method of claim 1, wherein the LBT metric is incremented for each failure to transmit on an uplink transmission instance.

15. The method of claim 1, wherein the LBT metric is incremented based on whether at least one failure to transmit on an uplink transmission instance occurred during a threshold period of time.

16. The method of claim 1, wherein the LBT metric is incremented based on a threshold number of uplink transmission failures occurring during a threshold time period.

17. The method of claim 1, wherein a threshold time period associated with identifying an LBT failure associated with the LBT metric ends based on a threshold number of successful uplink transmissions occurring during the threshold time period, and the LBT failure is not determined based on the threshold number of successful uplink transmissions occurring during the threshold time period.

18. The method of claim 1, wherein the LBT metric is at least one of:

an absolute metric representing at least one LBT failure in a measurement interval,

A ratio metric representing a ratio of LBT failures to opportunities at which LBT failures can occur in the measurement interval,

An absolute metric representing a threshold number of LBT failures that occurred in the measurement interval, or an absolute metric representing a number of LBT failures that occurred in the measurement interval.

19. The method of claim 18, wherein the measurement interval is at least one of:

a set of time slots,

A set of minislots,

Set of occasions in a single time slot, or

The channel occupancy time or the set of uplink grants in an uplink burst.

20. The method of claim 1, wherein the LBT metric is on a per LBT type basis.

21. The method of claim 20, wherein the LBT metric comprises a first LBT metric for class 4LBT and a second LBT metric for class 2 LBT.

22. The method of claim 21, wherein the first LBT metric and the second LBT metric are equally weighted to determine whether the LBT metric satisfies the LBT metric threshold.

23. The method of claim 21, wherein selectively triggering the recovery procedure comprises:

triggering the recovery procedure based on the first LBT metric satisfying a first threshold or the second LBT metric satisfying a second threshold.

24. The method of claim 21, wherein a first weight is applied to the first LBT metric and a second weight is applied to the second LBT metric to determine whether the LBT metric satisfies the LBT metric threshold, and

wherein at least one of the first weight or the second weight is determined based on at least one of:

the ratio of busy time slots of a corresponding channel to the total number of time slots of the corresponding channel,

Initial LBT counter value,

Congestion window size, or

A channel access priority class.

25. The method of claim 20, wherein the LBT metrics comprise a first LBT metric for an outer acquired Channel Occupancy Time (COT) LBT and a second LBT metric for an inner acquired COT LBT.

26. The method of claim 1, wherein the LBT metric is subband-specific or common to a plurality of subbands.

27. The method of claim 1, wherein the LBT metric is determined based on at least one of:

LBT failure across one or more sub-bands,

LBT success on one or more sub-bands, or

LBT fails on a single subband.

28. A method of wireless communication performed by an apparatus of a Base Station (BS), comprising:

configuring a second bandwidth portion for a User Equipment (UE) on a first bandwidth portion to enable a bandwidth portion switch for the UE and in conjunction with a listen-before-talk (LBT) metric, wherein the second bandwidth portion is different from an initial access bandwidth portion or a default bandwidth portion; and

receiving a report message indicating that the bandwidth partial handover is triggered by the UE after the LBT metric satisfies a threshold.

29. The method of claim 28, wherein the report message is at least one of a Radio Resource Control (RRC) message, a Medium Access Control (MAC) message, or a physical layer message.

30. The method of claim 28, wherein the report message includes information identifying at least one of:

bandwidth part switching trigger event, or

Number of LBT failures.

31. The method of claim 28, further comprising:

receiving a Random Access Channel (RACH) message after the bandwidth portion switch.

32. A User Equipment (UE) for wireless communication, comprising:

a memory; and

one or more processors operatively coupled to the memory, the memory and the one or more processors configured to:

performing a set of Listen Before Talk (LBT) procedures to access an unlicensed spectrum;

determining an LBT metric associated with an outcome of the set of LBT procedures; and

selectively triggering a recovery procedure based on the LBT metric satisfying an LBT metric threshold.

33. The UE of claim 32, wherein the LBT metric relates to a secondary cell, and

wherein the one or more processors, when selectively triggering the recovery process, are to:

sending a report indicating that the LBT metric satisfies the LBT metric threshold for the secondary cell.

34. The UE of claim 33, wherein the report includes information identifying at least one of:

the LBT metric,

A measurement report for the secondary cell,

A Channel Occupancy Time (COT) metric, or

A Received Signal Strength Indicator (RSSI) for the secondary cell.

35. The UE of claim 32, wherein the LBT metric is at least one of:

a metric related to the number of LBT failures,

A metric related to a channel busy status as a result of an LBT failure, or

A metric related to the amount of data lost as a result of LBT failure.

36. The UE of claim 32, wherein the LBT metric relates to a first bandwidth portion, and wherein the one or more processors are to, when selectively triggering the recovery procedure:

performing a bandwidth portion switch from the first bandwidth portion to a second bandwidth portion.

37. The UE of claim 36, wherein the second bandwidth portion is different from an initial access bandwidth portion or a default bandwidth portion.

38. The UE of claim 36, wherein the one or more processors are further configured to:

sending a report message to a serving cell indicating that the bandwidth part handover is triggered,

wherein the report message is at least one of: a Radio Resource Control (RRC) message, a Medium Access Control (MAC) message, or a physical layer message.

39. The UE of claim 38, wherein the report message includes information identifying at least one of:

bandwidth part switching trigger event, or

Number of LBT failures.

40. The UE of claim 36, wherein the one or more processors are further configured to:

sending a report message to a serving cell after the bandwidth part switching,

wherein the report message is a Random Access Channel (RACH) message.

41. A Base Station (BS) for wireless communication, comprising:

a memory; and

one or more processors operatively coupled to the memory, the memory and the one or more processors configured to:

configuring a second bandwidth portion for a User Equipment (UE) on a first bandwidth portion to enable a bandwidth portion switch for the UE and in conjunction with a listen-before-talk (LBT) metric, wherein the second bandwidth portion is different from an initial access bandwidth portion or a default bandwidth portion; and

receiving a report message indicating that the bandwidth partial handover is triggered by the UE after the LBT metric satisfies a threshold.

42. The BS of claim 41, wherein the report message is at least one of a Radio Resource Control (RRC) message, a Medium Access Control (MAC) message, or a physical layer message.

43. The BS of claim 41, wherein the report message includes information identifying at least one of:

bandwidth part switching trigger event, or

Number of LBT failures.

44. The BS of claim 41, wherein the one or more processors are further configured to:

receiving a Random Access Channel (RACH) message after the bandwidth portion switch.

45. A non-transitory computer-readable medium storing one or more instructions for wireless communication, the one or more instructions comprising:

one or more instructions that, when executed by one or more processors of a User Equipment (UE), cause the one or more processors to:

performing a set of Listen Before Talk (LBT) procedures to access an unlicensed spectrum;

determining an LBT metric associated with an outcome of the set of LBT procedures; and

selectively triggering a recovery procedure based on the LBT metric satisfying an LBT metric threshold.

46. The non-transitory computer-readable medium of claim 45, wherein the LBT metric relates to a secondary cell, and

wherein the one or more instructions that cause the one or more processors to selectively trigger the recovery process cause the one or more processors to:

sending a report indicating that the LBT metric satisfies the LBT metric threshold for the secondary cell.

47. The non-transitory computer-readable medium of claim 46, wherein the report includes information identifying at least one of:

the LBT metric,

A measurement report for the secondary cell,

A Channel Occupancy Time (COT) metric, or

A Received Signal Strength Indicator (RSSI) for the secondary cell.

48. The non-transitory computer-readable medium of claim 45, wherein the LBT metric is at least one of:

a metric related to the number of LBT failures,

A metric related to a channel busy status as a result of an LBT failure, or

A metric related to the amount of data lost as a result of LBT failure.

49. The non-transitory computer-readable medium of claim 45, wherein the LBT metric relates to a first bandwidth portion, and wherein the one or more instructions that cause the one or more processors to selectively trigger the recovery process cause the one or more processors to:

performing a bandwidth portion switch from the first bandwidth portion to a second bandwidth portion.

50. The non-transitory computer-readable medium of claim 49, wherein the second bandwidth portion is different from an initial access bandwidth portion or a default bandwidth portion.

51. The non-transitory computer-readable medium of claim 49, wherein the one or more instructions, when executed by the one or more processors, further cause the one or more processors to:

sending a report message to a serving cell indicating that the bandwidth part handover is triggered,

wherein the report message is at least one of: radio resource control

A (RRC) message, a Media Access Control (MAC) message, or a physical layer message.

52. The non-transitory computer-readable medium of claim 51, wherein the report message includes information identifying at least one of:

bandwidth part switching trigger event, or

Number of LBT failures.

53. The non-transitory computer-readable medium of claim 49, wherein the one or more instructions, when executed by the one or more processors, further cause the one or more processors to:

sending a report message to a serving cell after the bandwidth part switching,

wherein the report message is a Random Access Channel (RACH) message.

54. A non-transitory computer-readable medium storing one or more instructions for wireless communication, the one or more instructions comprising:

one or more instructions that when executed by one or more processors of a Base Station (BS) cause the one or more processors to:

configuring a second bandwidth portion for a User Equipment (UE) on a first bandwidth portion to enable a bandwidth portion switch for the UE and in conjunction with a listen-before-talk (LBT) metric, wherein the second bandwidth portion is different from an initial access bandwidth portion or a default bandwidth portion; and

receiving a report message indicating that the bandwidth partial handover is triggered by the UE after the LBT metric satisfies a threshold.

55. The non-transitory computer-readable medium of claim 54, wherein the report message is at least one of a Radio Resource Control (RRC) message, a Media Access Control (MAC) message, or a physical layer message.

56. The non-transitory computer-readable medium of claim 54, wherein the report message includes information identifying at least one of:

bandwidth part switching trigger event, or

Number of LBT failures.

57. The non-transitory computer-readable medium of claim 54, wherein the one or more instructions, when executed by the one or more processors, further cause the one or more processors to:

receiving a Random Access Channel (RACH) message after the bandwidth portion switch.

58. An apparatus for wireless communication, comprising:

means for performing a set of listen-before-talk (LBT) procedures to access an unlicensed spectrum;

means for determining an LBT metric associated with an outcome of the set of LBT procedures; and

means for selectively triggering a recovery procedure based on the LBT metric satisfying an LBT metric threshold.

59. The apparatus of claim 58, wherein the LBT metric relates to a secondary cell, and

wherein the means for selectively triggering the recovery procedure comprises:

means for transmitting a report indicating that the LBT metric satisfies the LBT metric threshold for the secondary cell.

60. The apparatus of claim 59, wherein the report comprises information identifying at least one of:

the LBT metric,

A measurement report for the secondary cell,

A Channel Occupancy Time (COT) metric, or

A Received Signal Strength Indicator (RSSI) for the secondary cell.

61. The apparatus of claim 58, wherein the LBT metric is at least one of:

a metric related to the number of LBT failures,

A metric related to a channel busy status as a result of an LBT failure, or

A metric related to the amount of data lost as a result of LBT failure.

62. The apparatus of claim 58, wherein the LBT metric relates to a first bandwidth portion, and wherein the means for selectively triggering the recovery procedure comprises:

means for performing a bandwidth portion switch from the first bandwidth portion to a second bandwidth portion.

63. The apparatus of claim 62, wherein the second bandwidth portion is different from an initial access bandwidth portion or a default bandwidth portion.

64. The apparatus of claim 62, further comprising:

means for sending a report message to a serving cell indicating that the bandwidth part handover is triggered,

wherein the report message is at least one of: a Radio Resource Control (RRC) message, a Medium Access Control (MAC) message, or a physical layer message.

65. The apparatus of claim 64, wherein the report message comprises information identifying at least one of:

bandwidth part switching trigger event, or

Number of LBT failures.

66. The apparatus of claim 62, further comprising:

means for sending a report message to a serving cell after the bandwidth part switch,

wherein the report message is a Random Access Channel (RACH) message.

67. An apparatus for wireless communication, comprising:

means for configuring a second bandwidth portion for a User Equipment (UE) on a first bandwidth portion to enable a bandwidth portion switch for the UE and in conjunction with a Listen Before Talk (LBT) metric, wherein the second bandwidth portion is different from an initial access bandwidth portion or a default bandwidth portion; and

means for receiving a report message indicating that the bandwidth partial handover is triggered by the UE after the LBT metric satisfies a threshold.

68. The apparatus of claim 67, wherein the report message is at least one of a Radio Resource Control (RRC) message, a Medium Access Control (MAC) message, or a physical layer message.

69. The apparatus of claim 67, wherein the report message comprises information identifying at least one of:

bandwidth part switching trigger event, or

Number of LBT failures.

70. The apparatus of claim 67, further comprising:

means for receiving a Random Access Channel (RACH) message following the bandwidth portion switch.

Technical Field

Aspects of the present disclosure relate generally to wireless communications, and more specifically to techniques for channel congestion measurement.

Background

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasting. A typical wireless communication system may employ multiple-access techniques capable of supporting communication with multiple users by sharing the available system resources (e.g., bandwidth, transmit power, etc.). Examples of such multiple-access techniques include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, time division synchronous code division multiple access (TD-SCDMA) systems, and Long Term Evolution (LTE). LTE/LTE-advanced is an enhanced set of Universal Mobile Telecommunications System (UMTS) mobile standards promulgated by the third generation partnership project (3 GPP).

A wireless communication network may include a plurality of Base Stations (BSs) capable of supporting communication for a plurality of User Equipments (UEs). A User Equipment (UE) may communicate with a Base Station (BS) via a Downlink (DL) and an Uplink (UL). The DL (or forward link) refers to the communication link from the BS to the UE, and the UL (or reverse link) refers to the communication link from the UE to the BS. As will be described in greater detail herein, a BS may be referred to as a node B, LTE evolved node B (enb), a gNB, an Access Point (AP), a radio head, a Transmit Receive Point (TRP), a New Radio (NR) BS, or a 5G node B.

The above multiple access techniques have been employed in various telecommunications standards to provide a common protocol that enables different UEs to communicate on a city, country, region, and even global level. NR (which may also be referred to as 5G) is an enhanced set of LTE mobile standards promulgated by the third generation partnership project (3 GPP). NR is designed to better integrate with other open standards, and support beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation, thereby better supporting mobile broadband internet access, by improving spectral efficiency, reducing costs, improving services, utilizing new spectrum, and using OFDM with Cyclic Prefix (CP) (CP-OFDM) on DL, CP-OFDM or SC-FDM (e.g., also known as discrete fourier transform spread OFDM (DFT-s-OFDM)) on UL (or a combination thereof).

Disclosure of Invention

The systems, methods, and devices of the present disclosure each have several innovative aspects, no single one of which is solely responsible for the desirable attributes disclosed herein.

One innovative aspect of the subject matter described in this disclosure can be embodied in a method of wireless communication performed by an apparatus of a User Equipment (UE). The method may include: performing a set of Listen Before Talk (LBT) procedures to access an unlicensed spectrum; determining an LBT metric associated with an outcome of the set of LBT procedures; and selectively triggering a recovery procedure based on the LBT metric satisfying an LBT metric threshold.

In some aspects, selectively triggering the recovery process includes at least one of: triggering one or more procedures related to Radio Link Failure (RLF), performing a recovery action, or reporting the LBT metric to a Base Station (BS). In some aspects, the LBT metric is an LBT failure metric. In some aspects, determining the LBT metric comprises: determining that an LBT failure occurred for an LBT procedure of the set of LBT procedures based on a failure with respect to transmitting on an uplink transmission instance. In some aspects, the uplink transmission instance is at least one of: physical Uplink Shared Channel (PUSCH) transmission, Physical Uplink Control Channel (PUCCH) transmission, or Physical Random Access Channel (PRACH) transmission, or Sounding Reference Signal (SRS) transmission.

In some aspects, the LBT metric is incremented for each failure with respect to transmitting on an uplink transmission instance. In some aspects, the LBT metric is incremented based on whether at least one failure to transmit on an uplink transmission instance occurred during a threshold period of time. In some aspects, the LBT metric is incremented based on a ratio of uplink transmission failure to uplink attempts during a threshold time period. In some aspects, the LBT metric is incremented based on a threshold number of uplink transmission failures occurring during a threshold time period. In some aspects, a threshold time period associated with identifying an LBT failure associated with the LBT metric ends based on a threshold number of successful uplink transmissions occurring during the threshold time period, and the LBT failure is not determined based on the threshold number of successful uplink transmissions occurring during the threshold time period.

In some aspects, the LBT metric is incremented based on whether at least one uplink transmission failure occurred during an evaluation period that includes uplink transmissions. In some aspects, the LBT metric is incremented based on a number of uplink transmission failures during the evaluation period. In some aspects, the LBT metric is incremented based on whether a number of uplink transmission failures during the evaluation period satisfies an uplink transmission failure threshold. In some aspects, an LBT failure associated with the LBT metric is not determined when a number of successful uplink transmissions during the evaluation period satisfies an uplink transmission threshold. In some aspects, the LBT metric is incremented based on an occurrence of a scheduled uplink transmission.

In some aspects, the scheduled uplink transmission comprises at least one uplink transmission instance and is at least one of an uplink grant, a PUCCH, or an uplink channel. In some aspects, the LBT metric is incremented based on an occurrence of an uplink transmission failure for each uplink transmission instance of the scheduled uplink transmission. In some aspects, the LBT metric is incremented based on whether an uplink transmission failure occurred in an uplink burst or channel occupancy time. In some aspects, the LBT metric is incremented based on the occurrence of the uplink transmission failure for each uplink transmission instance of the uplink burst or the channel occupancy time.

In some aspects, the LBT metric is at least one of: an absolute metric representing at least one LBT failure in a measurement interval, a ratio metric representing a ratio of LBT failures to opportunities in the measurement interval at which LBT failures can occur, an absolute metric representing a threshold number of LBT failures that occur in the measurement interval, or an absolute metric representing a number of LBT failures that occur in the measurement interval. In some aspects, the measurement interval is at least one of: a set of timeslots, a set of minislots, a set of occasions in a single timeslot, or a set of channel occupancy times or uplink grants in an uplink burst. In some aspects, the LBT metric is based on a per LBT type. In some aspects, the LBT metric comprises a first LBT metric for class 4LBT and a second LBT metric for class 2 LBT.

In some aspects, the first LBT metric and the second LBT metric are weighted equally to determine whether the LBT metric satisfies the LBT metric threshold. In some aspects, selectively triggering the recovery process comprises: triggering the recovery procedure based on the first LBT metric satisfying a first threshold or the second LBT metric satisfying a second threshold. In some aspects, a first weight is applied to the first LBT metric and a second weight is applied to the second LBT metric to determine whether the LBT metric satisfies the LBT metric threshold. In some aspects, at least one of the first weight or the second weight is determined based on at least one of: a ratio of busy time slots of a corresponding channel to a total number of time slots of the corresponding channel, an initial LBT counter value, a congestion window size, or a channel access priority class. In some aspects, the LBT metrics include a first LBT metric for an outer-acquired Channel Occupancy Time (COT) LBT and a second LBT metric for an inner-acquired COT LBT.

In some aspects, the LBT metric is subband-specific or common to multiple subbands. In some aspects, the LBT metric is determined based on at least one of: LBT failure on one or more subbands, LBT success on one or more subbands, or LBT failure on a single subband. In some aspects, the LBT metric relates to a secondary cell, and selectively triggering the recovery procedure comprises: sending a report indicating that the LBT metric satisfies the LBT metric threshold for the secondary cell. In some aspects, the report includes information identifying at least one of: the LBT metric, a measurement report for the secondary cell, a COT metric, or a Received Signal Strength Indicator (RSSI) for the secondary cell. In some aspects, the LBT metric is at least one of: a metric related to a number of LBT failures, a metric related to a channel busy status as a result of LBT failures, or a metric related to an amount of data lost as a result of LBT failures.

In some aspects, the LBT metric relates to a first bandwidth portion. In some aspects, selectively triggering the recovery process comprises: performing a bandwidth portion switch from the first bandwidth portion to a second bandwidth portion. In some aspects, the second bandwidth portion is different from the initial access bandwidth portion or the default bandwidth portion. In some aspects, the method may comprise: sending a report message to a serving cell indicating that the bandwidth part handover is triggered. In some aspects, the report message is at least one of: a Radio Resource Control (RRC) message, a Medium Access Control (MAC) message, or a physical layer message. In some aspects, the report message includes information identifying at least one of a bandwidth part switching trigger event or a number of LBT failures. In some aspects, the method may comprise: a report message is sent to a serving cell after the bandwidth part switching, and the report message may be a Random Access Channel (RACH) message.

Another innovative aspect of the subject matter described in this disclosure can be implemented in a UE for wireless communication. The UE may include a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to: performing a set of LBT procedures to access unlicensed spectrum; determining an LBT metric associated with an outcome of the set of LBT procedures; and selectively triggering a recovery procedure based on the LBT metric satisfying an LBT metric threshold.

Another innovative aspect of the subject matter described in this disclosure can be embodied in a non-transitory computer-readable medium. The non-transitory computer-readable medium may store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of the UE, may cause the one or more processors to: performing a set of LBT procedures to access unlicensed spectrum; determining an LBT metric associated with an outcome of the set of LBT procedures; and selectively triggering a recovery procedure based on the LBT metric satisfying an LBT metric threshold.

Another innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication. The apparatus may include: means for performing a set of LBT procedures to access unlicensed spectrum; means for determining an LBT metric associated with an outcome of the set of LBT procedures; and means for selectively triggering a recovery procedure based on the LBT metric satisfying an LBT metric threshold.

One innovative aspect of the subject matter described in this disclosure can be embodied in a method of wireless communication performed by an apparatus of a BS. The method may include: configuring a second bandwidth portion for a UE on a first bandwidth portion to enable a bandwidth portion switch for the UE and in conjunction with an LBT metric, wherein the second bandwidth portion is different from an initial access bandwidth portion or a default bandwidth portion; and receiving a report message indicating that the bandwidth partial handover is triggered by the UE after the LBT metric satisfies a threshold.

Another innovative aspect of the subject matter described in this disclosure can be implemented in a BS for wireless communication. The BS may include a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to: configuring a second bandwidth portion for a UE on a first bandwidth portion to enable a bandwidth portion switch for the UE and in conjunction with an LBT metric, wherein the second bandwidth portion is different from an initial access bandwidth portion or a default bandwidth portion; and receiving a report message indicating that the bandwidth partial handover is triggered by the UE after the LBT metric satisfies a threshold.

In some aspects, the report message is at least one of an RRC message, a MAC message, or a physical layer message. In some aspects, the report message includes information identifying at least one of a bandwidth part switching trigger event or a number of LBT failures. In some aspects, the method may comprise: receiving a RACH message after the bandwidth part switching.

Another innovative aspect of the subject matter described in this disclosure can be embodied in a non-transitory computer-readable medium. The non-transitory computer-readable medium may store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of the BS, may cause the one or more processors to: configuring a second bandwidth portion for a UE on a first bandwidth portion to enable a bandwidth portion switch for the UE and in conjunction with an LBT metric, wherein the second bandwidth portion is different from an initial access bandwidth portion or a default bandwidth portion; and receiving a report message indicating that the bandwidth partial handover is triggered by the UE after the LBT metric satisfies a threshold.

Another innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication. The apparatus may include: means for configuring a second bandwidth portion for a UE on a first bandwidth portion to enable a bandwidth portion switch for the UE and in conjunction with an LBT metric, wherein the second bandwidth portion is different from an initial access bandwidth portion or a default bandwidth portion; and means for receiving a report message indicating that the bandwidth partial handover is triggered by the UE after the LBT metric satisfies a threshold.

Aspects include, in general, methods, apparatuses, systems, computer program products, non-transitory computer-readable media, user equipment, base stations, wireless communication devices, and processing systems substantially as described herein with reference to and as illustrated by the accompanying drawings and description.

The foregoing has outlined rather broadly the features and technical advantages of examples according to the present disclosure in order that the detailed description that follows may be better understood. Additional features and advantages will be described hereinafter. The conception and specific examples disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. The nature of the concepts disclosed herein (both their organization and method of operation), together with the advantages associated therewith, will be better understood from the following description when considered in connection with the accompanying figures. Each of the figures is provided for the purposes of illustration and description and is not intended as a definition of the limits of the claims.

Drawings

Fig. 1 is a block diagram conceptually illustrating an example of a wireless network.

Fig. 2 is a block diagram conceptually illustrating an example of a Base Station (BS) communicating with a User Equipment (UE) in a wireless network.

Fig. 3A-3E are diagrams illustrating examples of channel congestion management.

Fig. 4 is a diagram illustrating an example process performed, for example, by a UE.

Fig. 5 is a diagram illustrating an example process performed by, for example, a BS.

Like reference numbers and designations in the various drawings indicate like elements.

Detailed Description

For the purpose of describing innovative aspects of the present disclosure, the following description is directed to certain implementations. However, those skilled in the art will readily appreciate that the teachings herein may be applied in a number of different ways. Some of the examples in this disclosure are based on wireless and wired Local Area Network (LAN) communications in accordance with the Institute of Electrical and Electronics Engineers (IEEE)802.11 wireless standard, the IEEE 802.3 ethernet standard, and the IEEE 1901 Power Line Communications (PLC) standard. However, the described implementations may be implemented in any device, system, or network capable of transmitting and receiving radio frequency signals according to any of the wireless communication standards including any of the following: IEEE 802.11 standard,Standard, Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), global system for mobile communications (GSM), GSM/General Packet Radio Service (GPRS), Enhanced Data GSM Environment (EDGE), terrestrial trunked radio (TETRA), wideband-CDMA (W-CDMA), evolution-data optimized (EV-DO), 1xEV-DO, EV-DO Rev a, EV-DO Rev B, High Speed Packet Access (HSPA), High Speed Downlink Packet Access (HSDPA), High Speed Uplink Packet Access (HSUPA), evolved high speed packet access (HSPA +), Long Term Evolution (LTE), AMPS, or for use in the wireless, cellular, or internet of things (IOT)Other known signals that communicate within a network, such as a system utilizing 3G, 4G, or 5G, or other implementations, techniques thereof.

Some wireless communication frequency ranges may be reserved for unlicensed spectrum. In some unlicensed spectrum deployment implementations, different operators or technologies may use different portions of the unlicensed spectrum simultaneously. Multiple operators may deploy, for example, NR networks, Wi-Fi networks, or LTE networks in a single location using unlicensed spectrum for communications. In such a case, each operator or technology may operate in a common location and use a common set of frequency bands, but still be independent of other operators or other technologies. For example, a first BS operated by a first operator may not be coordinated with a second BS operated by a second operator. In some other unlicensed spectrum deployment implementations, a single operator may deploy multiple ad hoc cells without a central entity to coordinate the multiple ad hoc cells. For example, a first BS operated by an operator and a second BS operated by the same operator may lack central coordination via a central entity.

To gain access to communication resources using unlicensed spectrum, a UE may perform a contention-based access procedure. For example, the UE may perform a listen-before-talk or transmit-before-talk (LBT) procedure to gain access to the communication resources. The LBT procedure may be a class 2LBT procedure for fixed duration sensing (Cat-2 LBT) or a class 4LBT procedure with variable duration sensing (Cat-4 LBT), where the variable duration is based on a priority class and a backoff period in which the UE detects interference. In some cases, a UE may experience an LBT failure when the UE fails to send an uplink transmission during an uplink transmission instance. For example, when an interfering node, such as another UE, attempts to access the same communication resources as the UE, the interfering node may send a transmission that interferes with the UE's uplink transmission. The UE may perform multiple consecutive LBT procedures when attempting to acquire resources.

Some aspects described herein provide for channel congestion measurement based on LBT failure. For example, the UE may determine the LBT metric based on LBT failures (such as an absolute number of LBT failures, a number of LBT failures within a particular measurement period, whether a particular measurement period includes a threshold number of LBT failures, a ratio of uplink transmission failures to successful uplink transmissions combined with the LBT procedure, and other possible types of LBT metrics). In this case, when the LBT metric threshold is met, the UE may trigger a recovery action, such as triggering an action related to Radio Link Failure (RLF), reporting the LBT metric or bandwidth partial handover to the BS.

Particular implementations of the subject matter described in this disclosure can be implemented to realize one or more of the following potential advantages. For example, the UE may avoid preemptively triggering a recovery action when the interfering node causes a relatively large number of LBT failures within a relatively short period of time. In this way, the UE may reduce network signaling relative to performing the recovery action in the event that the recovery action is not necessary because the LBT failure is temporary and limited to a relatively short period of time. Further, by triggering a bandwidth portion handover after a threshold LBT metric is met for a particular bandwidth portion, the UE may enable handover to another bandwidth portion with reduced interference, thereby improving network performance and UE performance.

Fig. 1 is a block diagram conceptually illustrating an example of a wireless network 100. The wireless network 100 may be an LTE network or some other wireless network (such as a 5G or NR network). Wireless network 100 may include a plurality of BSs 110 (shown as BS 110a, BS 110b, BS 110c, and BS 110d) and other network entities. A BS is an entity that communicates with User Equipment (UE) and may also be referred to as a base station, NR BS, node B, gNB, 5G node b (nb), access point, or Transmission Reception Point (TRP). Each BS may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" can refer to a coverage area of a BS, a BS subsystem serving the coverage area, or a combination thereof, depending on the context in which the term is used.

The BS may provide communication coverage for a macrocell, a picocell, a femtocell, another type of cell, or a combination thereof. A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscriptions. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscriptions. A femto cell may cover a relatively small geographic area (e.g., a residence) and may allow restricted access by UEs having an association with the femto cell (e.g., UEs in a Closed Subscriber Group (CSG)). The BS for the macro cell may be referred to as a macro BS. The BS for the pico cell may be referred to as a pico BS. The BS for the femto cell may be referred to as a femto BS or a home BS. In the example shown in fig. 1, BS 110a may be a macro BS for macro cell 102a, BS 110b may be a pico BS for pico cell 102b, and BS 110c may be a femto BS for femto cell 102 c. A BS may support one or more (e.g., three) cells. The terms "eNB", "base station", "NR BS", "gNB", "TRP", "AP", "node B", "5G NB" and "cell" may be used interchangeably herein.

In some examples, the cell may not necessarily be stationary, and the geographic area of the cell may move according to the location of the mobile BS. In some examples, the BSs may be interconnected to each other and to one or more other BSs or network nodes (not shown) in the wireless network 100 by various types of backhaul interfaces, such as direct physical connections using any suitable transport network, virtual networks, or a combination thereof.

Wireless network 100 may also include relay stations. A relay station is an entity that can receive a data transmission from an upstream station (e.g., a BS or a UE) and send the data transmission to a downstream station (e.g., a UE or a BS). A relay station may also be a UE that is capable of relaying transmissions for other UEs. In the example shown in fig. 1, relay station 110d may communicate with macro BS 110a and UE120 d to facilitate communication between BS 110a and UE120 d. The relay station may also be referred to as a relay BS, a relay base station, a relay, etc.

The wireless network 100 may be a heterogeneous network including different types of BSs (e.g., macro BSs, pico BSs, femto BSs, relay BSs, etc.). These different types of BSs may have different transmit power levels, different coverage areas, and different effects on interference in wireless network 100. For example, the macro BS may have a high transmit power level (e.g., 5 to 40 watts), while the pico BS, femto BS, and relay BS may have a lower transmit power level (e.g., 0.1 to 2 watts).

Network controller 130 may be coupled to a set of BSs and may provide coordination and control for these BSs. The network controller 130 may communicate with the BSs via a backhaul. BSs may also communicate with one another, directly or indirectly, e.g., via a wireless or wired backhaul.

UEs 120 (e.g., 120a, 120b, 120c) may be dispersed throughout wireless network 100, and each UE may be stationary or mobile. A UE may also be referred to as an access terminal, mobile station, subscriber unit, station, etc. The UE may be a cellular telephone (e.g., a smartphone), a Personal Digital Assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless telephone, a Wireless Local Loop (WLL) station, a tablet device, a camera, a gaming device, netbooks, smartbooks, ultrabooks, medical devices or appliances, biometric sensors/devices, wearable devices (smartwatches, smartclothing, smart glasses, smart wristbands, smart jewelry (e.g., smart rings, smart bracelets, etc.)), entertainment devices (e.g., music or video devices, or satellite radio units, etc.), vehicle components or sensors, smart meters/sensors, industrial manufacturing devices, global positioning system devices, or any other suitable device configured to communicate via a wireless or wired medium.

Some UEs may be considered Machine Type Communication (MTC) or evolved or enhanced machine type communication (eMTC) UEs. MTC and eMTC UEs include, for example, a robot, a drone, a remote device, a sensor, a meter, a monitor, a location tag, etc., which may communicate with a base station, another device (e.g., a remote device), or some other entity. The wireless node may provide a connection to or to a network (e.g., a wide area network such as the internet or a cellular network), for example, via a wired or wireless communication link. Some UEs may be considered internet of things (IoT) devices, or may be implemented as NB-IoT (narrowband internet of things) devices. Some UEs may be considered Customer Premises Equipment (CPE). UE120 may be included inside a housing that houses components of UE120, such as a processor component, a memory component, similar components, or a combination thereof.

In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a particular RAT and may operate on one or more frequencies. A RAT may also be referred to as a radio technology, air interface, etc. Frequencies may also be referred to as carriers, channels, etc. Each frequency may support a single RAT in a given geographic area in order to avoid interference between wireless networks of different RATs. In some cases, NR or 5G RAT networks may be deployed.

In some examples, access to an air interface may be scheduled, where a scheduling entity (e.g., a base station) allocates resources for communication between some or all of the devices and apparatuses within a service area or cell of the scheduling entity. Within this disclosure, the scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more subordinate entities, as discussed further below. That is, for scheduled communications, the subordinate entity utilizes the resources allocated by the scheduling entity.

The base station is not the only entity that can be used as a scheduling entity. That is, in some examples, a UE may serve as a scheduling entity that schedules resources for one or more subordinate entities (e.g., one or more other UEs). In this example, the UE is acting as a scheduling entity, while other UEs utilize the resources scheduled by the UE for wireless communication. The UE may act as a scheduling entity in a peer-to-peer (P2P) network, a mesh network, or another type of network. In the mesh network example, in addition to communicating with the scheduling entity, the UEs may optionally communicate directly with each other.

Thus, in a wireless communication network having scheduled access to time-frequency resources and having a cellular configuration, a P2P configuration, and a mesh configuration, a scheduling entity and one or more subordinate entities may communicate utilizing the scheduled resources.

In some aspects, two or more UEs 120 (e.g., shown as UE120 a and UE120e) may communicate directly using one or more sidelink (sidelink) channels (e.g., without using base station 110 as an intermediary to communicate with each other). For example, the UE120 may communicate using peer-to-peer (P2P) communication, device-to-device (D2D) communication, vehicle-to-anything (V2X) protocol (which may include vehicle-to-vehicle (V2V) protocol, vehicle-to-infrastructure (V2I) protocol, or the like), mesh network, or the like, or a combination thereof. In this case, UE120 may perform scheduling operations, resource selection operations, and other operations described elsewhere herein as being performed by base station 110.

Fig. 2 is a block diagram conceptually illustrating an example 200 of a base station 110 in communication with a UE 120. In some aspects, base station 110 and UE120 may be one of the base stations and one of the UEs, respectively, in wireless network 100 of fig. 1. The base station 110 may be equipped with T antennas 234a through 234T and the UE120 may be equipped with R antennas 252a through 252R, where T ≧ 1 and R ≧ 1 in general.

At base station 110, transmit processor 220 may receive data for one or more UEs from a data source 212, select one or more Modulation and Coding Schemes (MCSs) for each UE based on a Channel Quality Indicator (CQI) received from the UE, process (e.g., encode and modulate) the data for each UE based on the MCS selected for the UE, and provide data symbols for all UEs. Transmit processor 220 may also process system information (e.g., for semi-Static Resource Partitioning Information (SRPI), etc.) and control information (e.g., CQI requests, grants, upper layer signaling, etc.), as well as provide overhead symbols and control symbols. Transmit processor 220 may also generate reference symbols for reference signals (e.g., cell-specific reference signals (CRS)) and synchronization signals (e.g., Primary Synchronization Signals (PSS) and Secondary Synchronization Signals (SSS)). A Transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, the overhead symbols, or the reference symbols, if applicable, and may provide T output symbol streams to T Modulators (MODs) 232a through 232T. Each modulator 232 may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator 232 may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. T downlink signals from modulators 232a through 232T may be transmitted via T antennas 234a through 234T, respectively. According to various aspects described in greater detail below, a synchronization signal may be generated using position coding to convey additional information.

At UE120, antennas 252a through 252r may receive downlink signals from base station 110 or other base stations and may provide received signals to demodulators (DEMODs) 254a through 254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) a received signal to obtain input samples. Each demodulator 254 may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all R demodulators 254a through 254R, perform MIMO detection on the received symbols (if applicable), and provide detected symbols. A receive processor 258 may process (e.g., demodulate and decode) the detected symbols, provide decoded data for UE120 to a data sink 260, and provide decoded control information and system information to a controller or processor (controller/processor) 280. The channel processor may determine Reference Signal Received Power (RSRP), Received Signal Strength Indicator (RSSI), Reference Signal Received Quality (RSRQ), Channel Quality Indicator (CQI), and the like. In some aspects, one or more components of UE120 may be included in a housing.

On the uplink, at UE120, a transmit processor 264 may receive and process data from a data source 262 and control information from a controller/processor 280 (e.g., for reporting including RSRP, RSSI, RSRQ, CQI, etc.). Transmit processor 264 may also generate reference symbols for one or more reference signals. The symbols from transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by modulators 254a through 254r (e.g., for DFT-s-OFDM, CP-OFDM, etc.), and transmitted to base station 110. At base station 110, the uplink signals from UE120 and other UEs may be received by antennas 234, processed by demodulators 232, detected by a MIMO detector 236 (if applicable), and further processed by a receive processor 238 to obtain the decoded data and control information sent by UE 120. Receive processor 238 may provide the decoded data to a data sink 239 and the decoded control information to a controller or processor (i.e., controller/processor) 240. The base station 110 may include a communication unit 244 and communicate with the network controller 130 via the communication unit 244. Network controller 130 may include a communication unit 294, a controller or processor (i.e., controller/processor) 290, and a memory 292.

Controller/processor 240 of base station 110, controller/processor 280 of UE120, or any other component in fig. 2 may perform one or more techniques associated with channel congestion measurement, as described in more detail elsewhere herein. For example, controller/processor 240 of base station 110, controller/processor 280 of UE120, or any other component (or combination of components) in fig. 2 may perform or direct operations of, for example, process 400 of fig. 4, process 500 of fig. 5, or other processes as described herein. Memories 242 and 282 may store data and program codes for base station 110 and UE120, respectively. A scheduler 246 may schedule UEs for data transmission on the downlink, uplink, or a combination thereof.

In some aspects, UE120 may include: means for performing a set of listen-before-talk (LBT) procedures to access an unlicensed spectrum; means for determining an LBT metric associated with a set of results of an LBT procedure; means for selectively triggering a recovery procedure based on the LBT metric satisfying an LBT metric threshold; or a combination thereof. In some aspects, such means may include one or more components of UE120 described in conjunction with fig. 2.

In some aspects, base station 110 may comprise: means for configuring a second bandwidth portion to enable a bandwidth portion handover for a User Equipment (UE) and in conjunction with a listen-before-talk (LBT) metric, wherein the second bandwidth portion is different from an initial access bandwidth portion or a default bandwidth portion; means for receiving a report message indicating that a bandwidth partial handover is triggered by the UE after the LBT metric satisfies a threshold; or a combination thereof. In some aspects, such units may include one or more components of base station 110 described in conjunction with fig. 2.

While the blocks in fig. 2 are shown as distinct components, the functions described above with respect to the blocks may be implemented in a single hardware, software, or combination of components or in various combinations of components. For example, the functions described with respect to the transmit processor 264, the receive processor 258, the TX MIMO processor 266, or another processor may be performed by controller/processor 280 or under the control of controller/processor 280.

Fig. 3A-3E are diagrams illustrating an example 300 of channel congestion measurements. As shown in fig. 3A, example 300 includes UE120, one or more BSs 110, and one or more other UEs 120.

As shown in fig. 3A and by reference numeral 305, UE120 may perform a set of LBT procedures to attempt to access unlicensed spectrum resources of BS 110. For example, UE120 may perform an LBT procedure within a Channel Occupancy Time (COT) or outside of a COT. In some aspects, UE120 may perform a set of LBT procedures using a different set of frequency bands or using a different set of channel types. For example, UE120 may perform a first LBT procedure on a first frequency using a Physical Random Access Channel (PRACH), a second LBT procedure on a second frequency using a Physical Uplink Control Channel (PUCCH), or a third LBT procedure on a third frequency using a Physical Uplink Shared Channel (PUSCH).

In some aspects, UE120 may perform one or more successful LBT procedures. For example, UE120 may successfully send uplink communications associated with the LBT procedure, and may classify the LBT procedure as successful. Additionally or alternatively, UE120 may unsuccessfully transmit uplink communications associated with the LBT procedure, and may classify the LBT procedure as failed. In this case, the UE120 may unsuccessfully transmit uplink communications based on, for example, another UE120 performing an LBT procedure to attempt LBT-based access to the unlicensed spectrum resources. In some aspects, the UE120 may experience multiple failures within a threshold period of time. For example, during a burst set of transmissions, a UE120 may fail each transmission of the burst set based on another UE120 acquiring a channel on which the UE120 is attempting to transmit.

As shown in fig. 3A and by reference numeral 310, UE120 may determine an LBT metric based on the results of a set of LBT procedures. For example, UE120 may determine a number of LBT failures and increment an LBT metric by the number of LBT failures. In this case, UE120 may count each instance of uplink transmission independently to determine LBT failure. For example, when UE120 fails to transmit on an uplink transmission instance due to an LBT failure, UE120 may count the LBT failure and increment an LBT metric. In this case, UE120 may determine that the transmission is not complete based at least in part on expiration of the failure detection timer and may increment a counter. Conversely, when UE120 is able to transmit on an uplink transmission instance, UE120 may count LBT successes. In this case, the uplink transmission instance may include a PUSCH transmission instance, a PUCCH transmission instance, a PRACH transmission instance, or another type of uplink channel transmission instance. For example, when UE120 receives an uplink grant scheduling multiple PUSCHs, UE120 may count LBT failures for each PUSCH of the multiple PUSCHs that UE120 fails to transmit. In some aspects, UE120 may reset the LBT failure counter. For example, UE120 may reset the LBT failed counter to an initial value (0) based at least in part on expiration of a failure detection timer (no failure detected), reconfiguration of a failure detection timer, or reconfiguration of a counter.

In some aspects, UE120 may set a timer (such as a prohibit timer) and may determine the LBT metric based on one or more LBT failures or LBT successes within a time period tracked by the timer. For example, as shown in fig. 3B and by reference numeral 315-1, the timer may track a set of time periods during which uplink transmission instances may occur. In this case, when all uplink transmission instances for a particular period (such as the first and third periods) result in an LBT failure, the UE120 may determine the LBT failure for the particular period and may increment the LBT metric. Conversely, when at least one uplink transmission instance results in LBT success, such as in a second period or in a time period not tracked by the timer, UE120 may determine LBT success for the particular period and may not increment the LBT metric.

In some aspects, the UE120 may start the prohibit timer based on the occurrence of the LBT failure. For example, UE120 may start a prohibit timer to determine whether an uplink transmission success occurred within a threshold time period of an uplink transmission failure. In this case, the UE120 may stop the prohibit timer after a threshold period of time (and determine that an LBT failure has occurred) or after an uplink transmission success within the threshold period of time (and determine that an LBT success has occurred). In this case, each threshold time period results in UE120 determining a single LBT failure or success for the entire time period, rather than multiple LBT failures for multiple failed uplink transmission instances in the time period.

In some aspects, UE120 may increment the LBT metric based on a number of uplink failures during a threshold time period associated with the prohibit timer. For example, UE120 may increment the LBT metric by a ratio of uplink transmission failures to total uplink transmission attempts during a threshold time period. Additionally or alternatively, UE120 may increment the LBT metric based on whether a number of uplink transmission failures satisfies a threshold. For example, rather than determining that LBT failed when all uplink transmission attempts for a particular time period failed, UE120 may determine that LBT failed when a threshold number of uplink transmission attempts failed. As one example, when the threshold number is two uplink transmission failures, the UE120 may determine an LBT failure for the first time period, but may not determine an LBT failure for the third time period. Additionally or alternatively, UE120 may stop the prohibit timer and determine that LBT was successful based on a threshold number of successful uplink transmissions occurring during a threshold time period, and may determine the LBT metric based on the number of LBT successes. In some cases, the prohibit timer may be associated with an uplink transmission success period instead of an uplink transmission failure period.

In some aspects, UE120 may use the set of evaluation periods to determine whether to increment the LBT metric based on the LBT failure. For example, as shown in fig. 3C and by reference numeral 315-2, UE120 may divide the time period into a set of evaluation periods of equal size, and a single LBT result (LBT failure or LBT success) may be determined for each evaluation period. In this case, for example, UE120 may determine that LBT failed for periods 1 and 5 (in which unsuccessful uplink transmission occurred and no successful uplink transmission occurred), determine that LBT succeeded for periods 2 and 3 (in which at least one successful uplink transmission occurred), and determine nothing for period 4 (in which neither successful uplink transmission nor unsuccessful uplink transmission occurred). In some aspects, the evaluation periods may have different sizes or may overlap in time.

Additionally or alternatively, UE120 may increment the LBT metric by a fraction of uplink transmission failures and total uplink transmission attempts for each evaluation period. Additionally or alternatively, the UE120 may determine an LBT failure for a particular evaluation period when the number of uplink transmission failures satisfies a threshold number. Additionally or alternatively, the UE120 may determine that LBT was successful for a particular evaluation period when the number of uplink transmission successes satisfies a threshold. In some aspects, the UE120 may determine that LBT failed or succeeded when a minimum number of LBT failures or successes are observed. For example, UE120 may forgo incrementing the LBT metric when only a single uplink transmission failure occurs in a single uplink transmission instance of the evaluation period.

In some aspects, UE120 may determine the LBT metric based on the scheduled uplink transmission. For example, as shown in fig. 3D and by reference numeral 315-3, UE120 may receive a set of Downlink Control Information (DCI) including information identifying an uplink grant, PUSCH transmission instance, or other uplink channel transmission. In this case, when UE120 fails to successfully perform uplink transmission during any instance scheduled by the DCI, UE120 may determine that LBT failed and increment the LBT metric. For example, after the first DCI, UE120 may determine an LBT failure and increment an LBT metric based on each uplink transmission attempt being a failure. Conversely, after the second DCI, UE120 may determine that LBT was successful based on at least one uplink transmission success. Additionally or alternatively, UE120 may determine the LBT metric based on other determinations related to the scheduled uplink transmission, such as based on a ratio of uplink transmission failure to uplink transmission success, or based on a threshold number of uplink transmission failures or uplink transmission successes.

In some aspects, UE120 may determine the LBT metric based on a set of uplink transmission bursts or COTs. For example, as shown in fig. 3E and by reference numeral 315-4, UE120 may attempt to transmit during multiple uplink transmission bursts or COTs. In this case, when each uplink transmission attempt in an uplink transmission burst or COT is a failure, UE120 may determine that LBT failed and may increment the LBT metric. Conversely, the UE120 may determine that the LBT was successful when at least one uplink transmission attempt in the uplink transmission burst or COT was successful. Additionally or alternatively, UE120 may determine the LBT metric based on other determinations related to the uplink burst or COT, such as incrementing the LBT metric by a ratio of uplink transmission failure to uplink transmission success, or determining the LBT metric based on a threshold number of uplink transmission failures or uplink transmission successes in the uplink burst or COT.

In some aspects, the UE120 may determine the LBT metric based on the uplink transmission starting point. For example, when UE120 may be able to successfully perform uplink transmission at any available uplink transmission starting point, UE120 may determine that LBT was successful and increment the LBT metric. Additionally or alternatively, UE120 may increment the LBT metric by a ratio of a number of starting points to a total number of starting points for which UE120 unsuccessfully attempted to perform uplink transmission. Additionally or alternatively, when a threshold percentage or number of starting points is associated with unsuccessful uplink transmission attempts, UE120 may determine that LBT was successful and increment the LBT metric. Additionally or alternatively, rather than on a per starting point basis, UE120 may determine LBT metrics on a slot basis, a micro-slot basis, or on an uplink grant basis. For example, UE120 may determine LBT success and increment the LBT metric based on using multiple starting points within a single time slot, multiple starting points within an uplink grant or uplink burst or COT, multiple time slots within an uplink grant or uplink burst or COT, or multiple uplink grants within an uplink burst or COT.

In some aspects, UE120 may determine a plurality of different LBT metrics. For example, UE120 may determine a first LBT metric for a category 2LBT (Cat-2 LBT) based uplink transmission attempt and a second LBT metric for a category 4LBT (Cat-4 LBT) based uplink transmission attempt. In some aspects, UE120 may determine a first LBT metric for uplink transmission attempts within the obtained COT and a second LBT metric for uplink transmission attempts other than the obtained COT. Additionally or alternatively, UE120 may determine a first LBT metric for a first subband and a second LBT metric for a second subband. In this case, the UE120 may perform Cat-4LBT on a primary subband in the first and second subbands and Cat-2LBT on a secondary subband in the first and second subbands. Additionally or alternatively, UE120 may perform Cat-4LBT on both the first and second subbands.

Additionally or alternatively, UE120 may determine the LBT metric based on the UE capabilities. For example, when the UE capabilities of UE120 enable transmission on a subset of subbands, UE120 may determine that LBT was successful when Cat-4LBT or Cat-2LBT was successful on a first subset of subbands and unsuccessful on a second subset of subbands. Conversely, for different capabilities, when UE120 is only able to perform uplink transmission if the LBT procedure is successful on each sub-band, UE120 may determine that LBT failed if Cat-2LBT or Cat-4LBT is unsuccessful on any sub-band. In some aspects, UE120 may determine a different LBT metric for each subband or a common LBT metric for multiple subbands.

As shown in fig. 3A and by reference numeral 320, UE120 may selectively trigger a recovery procedure based on LBT metrics. For example, as indicated by reference numeral 320', UE120 may communicate with BS 110 to trigger a Radio Link Failure (RLF) based recovery action, a bandwidth segment switch, or another type of recovery action.

In some aspects, UE120 may determine to trigger a recovery procedure based on the LBT metric satisfying a threshold. For example, an LBT metric representing a number of LBT failures may exceed an absolute threshold, an LBT metric representing a ratio of unsuccessful uplink transmission attempts to uplink transmission opportunities may satisfy a ratio threshold for a threshold period of time, or may satisfy another type of threshold. In some aspects, UE120 may determine that the threshold is met based on one or more of the plurality of LBT metrics. For example, UE120 may determine that an equally weighted combination of the Cat-4LBT metric and the Cat-2LBT metric exceeds a combining threshold. Additionally or alternatively, UE120 may determine that the Cat-4LBT metric satisfies the first threshold or that the Cat-2LBT metric satisfies the second threshold. In this case, UE120 may report the Cat-4LBT metric, the Cat-2LBT metric, or a combination of the Cat-2LBT metric and the Cat-4LBT metric when triggering the recovery procedure. Additionally or alternatively, UE120 may determine that a particular sub-band LBT metric satisfies a threshold and may trigger a recovery procedure.

Additionally or alternatively, when combining the Cat-2LBT metric and the Cat-4LBT metric in determining whether the combination threshold is met, UE120 may apply different weights to the Cat-2LBT metric and the Cat-4LBT metric. For example, UE120 may apply the weights based on a percentage of time each channel for Cat-2LBT or Cat-4LBT is sensed as busy based on an uplink transmission failure, an initial LBT counter value, a congestion window size, or a channel access priority class.

In some aspects, based on determining that the LBT metric is satisfied, the UE120 may trigger a bandwidth partial handover. For example, UE120 may switch from a first bandwidth portion on which UE120 is operating to a second bandwidth portion configured by BS 110, BS 110 being the serving cell for UE 120. In some aspects, UE120 may switch to a bandwidth portion that is not the initial access bandwidth portion or the default bandwidth portion. For example, UE120 may switch from an initial access bandwidth portion of a relatively narrow bandwidth to a different bandwidth portion of a relatively wide bandwidth. Additionally or alternatively, UE120 may perform a Random Access Channel (RACH) procedure after the bandwidth portion handover (and without indicating the bandwidth portion handover to BS 110 at an earlier time).

In some aspects, when uplink resources are configured or granted for UE120, UE120 may send a message to BS 110 indicating a bandwidth portion switch. For example, UE120 may send a Radio Resource Control (RRC), Medium Access Control (MAC), or physical layer message to indicate the bandwidth portion switch. In this case, UE120 may include information indicating that the bandwidth partial handover is based on the LBT metric satisfying the threshold or information identifying a number of LBT failures.

In some aspects, rather than triggering a recovery action, UE120 may send a message indicating that the LBT metric satisfies the threshold. For example, when UE120 determines that the LBT metric is satisfied on the secondary cell rather than the primary cell, UE120 may indicate to BS 110 that the LBT metric is satisfied and may avoid triggering an RLF-based recovery action. In this case, UE120 may indicate that an LBT failure has occurred, may identify an LBT failure metric, may perform network measurements and provide measurement reports for the secondary cells, or may include other metrics such as a COT metric or a Received Signal Strength Indicator (RSSI).

Fig. 4 is a diagram illustrating an example process 400 performed, for example, by a UE. The example process 400 illustrates operations in which a UE (such as UE 120) performs associated with channel congestion measurements.

As shown in fig. 4, in some aspects, process 400 may include: a set of LBT procedures is performed to access the unlicensed spectrum (block 410). For example, the UE (using receive processor 258, transmit processor 264, controller/processor 280, or memory 282) may perform a set of LBT procedures to access the unlicensed spectrum. In some aspects, a UE may include an interface to perform a set of LBT procedures.

As shown in fig. 4, in some aspects, process 400 may include: LBT metrics associated with results of a set of LBT procedures are determined (block 420). For example, the UE (using receive processor 258, transmit processor 264, controller/processor 280, or memory 282) may determine LBT metrics associated with the results of a set of LBT procedures. In some aspects, a UE may include an interface for determining LBT metrics.

As shown in fig. 4, in some aspects, process 400 may include: a recovery process is selectively triggered based on the LBT metric satisfying the LBT metric threshold (block 430). For example, the UE (using receive processor 258, transmit processor 264, controller/processor 280, or memory 282) may selectively trigger a recovery procedure based on the LBT metric satisfying the LBT metric threshold. In some aspects, a UE may include an interface to selectively trigger a recovery procedure.

Process 400 may include additional aspects, such as any single method or any combination of the aspects described below or in conjunction with one or more other processes described elsewhere herein.

In a first aspect, selectively triggering the recovery procedure includes at least one of: trigger one or more RLF related procedures, perform recovery actions, or report LBT metrics to the BS.

In a second aspect (alone or in combination with the first aspect), the LBT metric is an LBT failure metric.

In a third aspect (alone or in combination with one or more of the first and second aspects), determining the LBT metric comprises: determining that an LBT failure occurred for an LBT procedure in a set of LBT procedures based on a failure with respect to transmitting on an uplink transmission instance.

In a fourth aspect (alone or in combination with one or more of the first through third aspects), the uplink transmission instance is at least one of: a PUSCH transmission, a PUCCH transmission, or a PRACH transmission, or an SRS transmission.

In a fifth aspect (alone or in combination with one or more of the first through fourth aspects), the LBT metric is incremented for each failure to transmit on an uplink transmission instance.

In a sixth aspect (alone or in combination with one or more of the first through fifth aspects), the LBT metric is incremented based on whether at least one failure to transmit on an uplink transmission instance occurred during a threshold period of time.

In a seventh aspect (alone or in combination with one or more of the first through sixth aspects), the LBT metric is incremented based on a ratio of uplink transmission failure to uplink attempt during a threshold time period.

In an eighth aspect (alone or in combination with one or more of the first through seventh aspects), the LBT metric is incremented based on a threshold number of uplink transmission failures occurring during a threshold time period.

In a ninth aspect (alone or in combination with one or more of the first through eighth aspects), the threshold period associated with identifying an LBT failure associated with the LBT metric ends based on a threshold number of successful uplink transmissions occurring during the threshold period, and the LBT failure is not determined based on the threshold number of successful uplink transmissions occurring during the threshold period.

In a tenth aspect (alone or in combination with one or more of the first through ninth aspects), the LBT metric is incremented based on whether at least one uplink transmission failure occurred during an evaluation period that includes the uplink transmission.

In an eleventh aspect (alone or in combination with one or more of the first through tenth aspects), the LBT metric is incremented based on a number of uplink transmission failures during the evaluation period.

In a twelfth aspect (alone or in combination with one or more of the first through eleventh aspects), the LBT metric is incremented based on whether a number of uplink transmission failures during the evaluation period satisfies an uplink transmission failure threshold.

In a thirteenth aspect (alone or in combination with one or more of the first through twelfth aspects), the LBT failure associated with the LBT metric is not determined when a number of successful uplink transmissions during the evaluation period satisfies an uplink transmission threshold.

In a fourteenth aspect (alone or in combination with one or more of the first through thirteenth aspects), the LBT metric is incremented based on an occurrence of a scheduled uplink transmission.

In a fifteenth aspect (alone or in combination with one or more of the first to fourteenth aspects), the scheduled uplink transmission comprises at least one uplink transmission instance and is at least one of an uplink grant, a PUCCH or an uplink channel.

In a sixteenth aspect (alone or in combination with one or more of the first through fifteenth aspects), the LBT metric is incremented based on an occurrence of an uplink transmission failure for each uplink transmission instance of the scheduled uplink transmission.

In a seventeenth aspect (alone or in combination with one or more of the first through sixteenth aspects), the LBT metric is incremented based on whether an uplink transmission failure occurred in an uplink burst or channel occupancy time.

In an eighteenth aspect (alone or in combination with one or more of the first through seventeenth aspects), the LBT metric is incremented based on an occurrence of an uplink transmission failure for each uplink transmission instance of an uplink burst or channel occupancy time.

In a nineteenth aspect (alone or in combination with one or more of the first through eighteenth aspects), the LBT metric is at least one of: an absolute metric representing at least one LBT failure in a measurement interval, a ratio metric representing a ratio of LBT failures to opportunities in the measurement interval at which LBT failures can occur, an absolute metric representing a threshold number of LBT failures that occur in the measurement interval, or an absolute metric representing a number of LBT failures that occur in the measurement interval.

In a twentieth aspect (alone or in combination with one or more of the first to nineteenth aspects), the measurement interval is at least one of: a set of timeslots, a set of minislots, a set of occasions in a single timeslot, or a set of channel occupancy times or uplink grants in an uplink burst.

In a twenty-first aspect (alone or in combination with one or more of the first through twentieth aspects), the LBT metric is based on per LBT type.

In a twenty-second aspect (alone or in combination with one or more of the first through twenty-first aspects), the LBT metrics comprise a first LBT metric for class 4LBT and a second LBT metric for class 2 LBT.

In a twenty-third aspect (alone or in combination with one or more of the first through twenty-second aspects), the first LBT metric and the second LBT metric are equally weighted to determine whether the LBT metric satisfies the LBT metric threshold.

In a twenty-fourth aspect (alone or in combination with one or more of the first through twenty-third aspects), selectively triggering the recovery process comprises: triggering a recovery procedure based on the first LBT metric satisfying a first threshold or the second LBT metric satisfying a second threshold.

In a twenty-fifth aspect (alone or in combination with one or more of the first through twenty-fourth aspects), a first weight is applied to the first LBT metric and a second weight is applied to the second LBT metric to determine whether the LBT metric satisfies the LBT metric threshold. In some aspects, at least one of the first weight or the second weight is determined based on at least one of: a ratio of busy time slots of the corresponding channel to a total number of time slots of the corresponding channel, an initial LBT counter value, a congestion window size, or a channel access priority class.

In a twenty-sixth aspect (alone or in combination with one or more of the first through twenty-fifth aspects), the LBT metrics comprise a first LBT metric for an outer acquired COT LBT and a second LBT metric for an inner acquired COT LBT.

In a twenty-seventh aspect (alone or in combination with one or more of the first through twenty-sixth aspects), the LBT metric is subband-specific or common to multiple subbands.

In a twenty-eighth aspect (alone or in combination with one or more of the first through twenty-seventh aspects), the LBT metric is determined based on at least one of: LBT failure on one or more subbands, LBT success on one or more subbands, or LBT failure on a single subband.

In a twenty-ninth aspect (alone or in combination with one or more of the first through twenty-eighth aspects), the LBT metric is related to a secondary cell, and selectively triggering the recovery procedure comprises: sending a report indicating that the LBT metric satisfies an LBT metric threshold for the secondary cell.

In a thirty-third aspect (alone or in combination with one or more of the first through twenty-ninth aspects), the report includes information identifying at least one of: LBT metric, measurement report for secondary cell, COT metric, or RSSI for secondary cell.

In a thirty-first aspect (alone or in combination with one or more of the first through thirty-first aspects), the LBT metric is at least one of: a metric related to a number of LBT failures, a metric related to a channel busy status as a result of LBT failures, or a metric related to an amount of data lost as a result of LBT failures.

In a thirty-second aspect (alone or in combination with one or more of the first through thirty-first aspects), the LBT metric relates to the first bandwidth portion. In some aspects, selectively triggering the recovery process includes: a bandwidth part switch is performed from the first bandwidth part to the second bandwidth part.

In a thirty-third aspect (alone or in combination with one or more of the first through thirty-second aspects), the second bandwidth portion is different from the initial access bandwidth portion or the default bandwidth portion.

In a thirty-fourth aspect (alone or in combination with one or more of the first through thirty-third aspects), the process 400 may comprise: a report message is sent to the serving cell indicating that a bandwidth portion handover is triggered. In some aspects, the report message is at least one of: RRC messages, MAC messages, or physical layer messages.

In a thirty-fifth aspect (alone or in combination with one or more of the first through thirty-fourth aspects), the report message includes information identifying at least one of a bandwidth part handover trigger event or a number of LBT failures.

In a thirty-sixth aspect (alone or in combination with one or more of the first through thirty-fifth aspects), the process 400 may comprise: the report message is sent to the serving cell after the bandwidth portion handover, and may be a RACH message.

Although fig. 4 shows example blocks of the process 400, in some aspects the process 400 may include additional blocks, fewer blocks, different blocks, or blocks arranged in a different manner than those depicted in fig. 4. Additionally or alternatively, two or more of the blocks of process 400 may be performed in parallel.

Fig. 5 is a diagram illustrating an example process 500 performed, for example, by a BS. Example process 500 illustrates an operation in which a BS, such as BS 110, performs associated channel congestion measurements.

As shown in fig. 5, in some aspects, process 500 may include: configuring a second bandwidth portion for the UE on the first bandwidth portion to enable a bandwidth portion handover for the UE and in conjunction with the LBT metric, wherein the second bandwidth portion is different from the initial access bandwidth portion or the default bandwidth portion (block 510). For example, the BS (using transmit processor 220, receive processor 238, controller/processor 240, or memory 242) may configure the second bandwidth portion for the UE on the first bandwidth portion to enable a bandwidth portion switch for the UE and in conjunction with the LBT metric. In some aspects, the second bandwidth portion is different from the initial access bandwidth portion or the default bandwidth portion. In some aspects, the BS may include an interface to configure the second bandwidth portion.

As shown in fig. 5, in some aspects, process 500 may include: a report message is received indicating that a bandwidth partial handover is triggered by the UE after the LBT metric satisfies the threshold (block 520). For example, the BS (using transmit processor 220, receive processor 238, controller/processor 240, or memory 242) may receive a report message indicating that a bandwidth portion switch was triggered by the UE after the LBT metric satisfies the threshold. In some aspects, a BS may include an interface for receiving a report message.

Process 500 may include additional aspects, such as any single method or any combination of the aspects described below or in conjunction with one or more other processes described elsewhere herein.

In the first aspect, the report message is at least one of an RRC message, a MAC message, or a physical layer message.

In a second aspect (alone or in combination with the first aspect), the report message comprises information identifying at least one of a bandwidth part handover trigger event or a number of LBT failures.

In a third aspect (alone or in combination with one or more of the first and second aspects), the process 500 may include: receiving a RACH message after the bandwidth part switching.

Although fig. 5 shows example blocks of the process 500, in some aspects the process 500 may include additional blocks, fewer blocks, different blocks, or blocks arranged in a different manner than those depicted in fig. 5. Additionally or alternatively, two or more of the blocks of the process 500 may be performed in parallel.

The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit aspects to the precise form disclosed. Modifications and variations are possible in light of the above disclosure or may be acquired from practice of various aspects.

As used herein, the term "component" is intended to be broadly interpreted as hardware, firmware, or a combination of hardware and software. As used herein, a processor is implemented in hardware, firmware, or a combination of hardware and software. As used herein, the phrase "based on" is intended to be broadly interpreted to mean "based, at least in part, on.

As used herein, meeting a threshold may refer to a value greater than the threshold, greater than or equal to the threshold, less than or equal to the threshold, or not equal to the threshold, depending on the context.

As used herein, a phrase referring to "at least one of a list of items refers to any combination of those items, including a single member. For example, "at least one of a, b, or c" is intended to encompass: a. b, c, a-b, a-c, b-c and a-b-c.

The various illustrative logical units, logical blocks, modules, circuits, and algorithm processes described in connection with the aspects disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. The interchangeability of hardware and software has been described generally in terms of functionality and illustrated in the various illustrative components, blocks, modules, circuits, and processes described above. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

The hardware and data processing apparatus used to implement the various illustrative logical units, logical blocks, modules, and circuits described in connection with the aspects disclosed herein may be implemented or performed with a general purpose single-or multi-chip processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor or any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. In some aspects, certain processes and methods may be performed by circuitry that is specific to a given function.

In one or more aspects, the functions described may be implemented in hardware, digital electronic circuitry, computer software, firmware, including the structures disclosed in this specification and their structural equivalents, or any combination thereof. Aspects of the subject matter described in this specification can also be implemented as one or more computer programs, i.e., one or more modules of computer program instructions, encoded on computer storage media for execution by, or to control the operation of, data processing apparatus.

If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code in a computer-readable medium. The processes of the methods or algorithms disclosed herein may be implemented in processor-executable software modules, which may reside on computer-readable media. Computer-readable media includes both computer storage media and communication media including any medium that can be used to transfer a computer program from one place to another. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. Further, any connection is properly termed a computer-readable medium. Disk and disc, as used herein, includes Compact Disc (CD), laser disc, optical disc, Digital Versatile Disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs usually reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media. Additionally, the operations of a method or algorithm may reside as one or any combination or set of codes and instructions on a machine readable medium and computer readable medium, which may be incorporated into a computer program product.

Various modifications to the aspects described in this disclosure may be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects without departing from the spirit or scope of the disclosure. Thus, the claims are not intended to be limited to the aspects shown herein but are to be accorded the widest scope consistent with the present disclosure, the principles and novel features disclosed herein.

In addition, those of ordinary skill in the art will readily appreciate that the terms "upper" and "lower" are sometimes used for ease of describing the figures, and indicate relative positions corresponding to the orientation of the figures on a properly oriented page, and may not reflect the correct orientation of any device implemented.

Certain features that are described in this specification in the context of separate aspects can also be implemented in combination in a single aspect. Conversely, various features that are described in the context of a single aspect can also be implemented in multiple aspects separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Further, the figures may schematically depict one or more example processes in the form of a flow diagram. However, other operations not depicted may be incorporated in the example process schematically shown. For example, one or more additional operations may be performed before, after, concurrently with, or between any of the illustrated operations. In some cases, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the aspects described above should not be understood as requiring such separation in all aspects, but rather should be understood to mean that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products. Still other aspects are within the scope of the following claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve desirable results.