Narrowband communications in unlicensed frequency band
This disclosure provides systems, methods and apparatus, including computer programs encoded on computer storage media, for narrowband communications using frequency hopping in an unlicensed frequency band. In some aspects, a base station (BS) and a user equipment (UE) may communicate with one another over a sequence of unique frequency sub-bands of a frequency hopping pattern. In some instances, the BS and the UE may switch from a current frequency sub-band to another frequency sub-band based on a number of unsuccessful attempts to gain access to the current frequency sub-band. In some other instances, the BS and the UE may communicate data using configured grant (CG) resources based on a number of unsuccessful attempts to gain access to the current frequency sub-band.
1. A method performed by an apparatus of a user equipment (UE), comprising:
receiving a discovery reference signal (DRS) indicating a frequency hopping pattern including a sequence of frequency sub-bands;
receiving an indication of one or more clear channel assessment (CCA) parameters, the one or more CCA parameters indicating an initial slot position associated with transmissions over at least a first frequency sub-band of the sequence of frequency sub-bands, a maximum quantity of CCA procedures to be performed when gaining access to one or more respective frequency sub-bands of the sequence of frequency sub-bands, or both; and
monitoring for a signal indicating a channel occupancy time (COT) on the first frequency sub-band of the sequence of frequency sub-bands based at least in part on the maximum quantity of CCA procedures to be performed.
2. The method of claim 1 , wherein the DRS is received over an anchor channel of an unlicensed frequency band.
3. The method of claim 1 , wherein a result of the monitoring is a failure to detect the signal indicating the COT within a time period associated with the maximum quantity of CCA procedures, the method further comprising:
transmitting at least a portion of a series of data frames using configured grant (CG) resources based at least in part on the failure to detect the signal indicating the COT within the time period.
4. The method of claim 1 , wherein the signal comprises one or more of a system information channel occupancy time (SI-COT), a group-common physical downlink control channel (GC-PDCCH), or a common transmit preamble.
5. The method of claim 1 , wherein monitoring for the signal indicating the COT is based at least in part on one of a CCA procedure or an extended CCA procedure performed on the first frequency sub-band.
6. The method of claim 1 , wherein an initial slot position of the DRS is based on a quantity of CCA and extended CCA procedures performed to gain access to a channel over which the DRS is received, and wherein an initial slot position of a first data frame is based on the quantity of CCA and extended CCA procedures performed to gain access to the first frequency sub-band.
7. The method of claim 1 , further comprising:
switching to another frequency sub-band of the sequence of frequency sub-bands after a quantity of unsuccessful CCA procedures are performed on the first frequency sub-band, the quantity of unsuccessful CCA procedures based at least in part on the maximum quantity of CCA procedures to be performed; or
transmitting at least a portion of a series of data frames using configured grant (CG) resources after the quantity of unsuccessful extended CCA procedures on the first frequency sub-band, the quantity of unsuccessful CCA procedures based at least in part on the maximum quantity of CCA procedures to be performed.
8. The method of claim 7 , wherein each data frame of the series of data frames is preceded by a corresponding DRS and is communicated over a respective frequency sub-band of the sequence of frequency sub-bands.
9. The method of claim 1 , wherein the DRS includes a slot format indicator (SFI) and includes enhanced remaining minimum system information (eRMSI) indicating the frequency hopping pattern and each of the frequency sub-bands.
10. The method of claim 1 , wherein:
a first symbol of the DRS is punctured to facilitate a clear channel assessment (CCA) procedure associated with transmission of the DRS; or
a last symbol of the DRS is punctured to facilitate a CCA procedure associated with transmission of a first data frame from the UE.
11. The method of claim 1 , further comprising at least one of:
puncturing a first symbol of a first data frame of a series of data frames to facilitate a clear channel assessment (CCA) procedure associated with transmission of the first data frame; or
puncturing a last symbol of the first data frame to facilitate a CCA procedure associated with transmission of a subsequent DRS from an access network node.
12. A wireless communication device, comprising:
an interface configured to:
obtain a discovery reference signal (DRS) indicating a frequency hopping pattern including a sequence of frequency sub-bands; and
obtain an indication of one or more clear channel assessment (CCA) parameters, the one or more CCA parameters indicating an initial slot position associated with transmissions over at least a first frequency sub-band of the sequence of frequency sub-bands, a maximum quantity of CCA procedures to be performed when gaining access to one or more respective frequency sub-bands of the sequence of frequency sub-bands, or both; and
a processing system configured to:
monitor for a signal indicating a channel occupancy time (COT) on the first frequency sub-band of the sequence of frequency sub-bands based at least in part on the maximum quantity of CCA procedures to be performed.
13. The wireless communication device of claim 12 , wherein the DRS is received over an anchor channel of an unlicensed frequency band, and the signal comprises one or more of a system information channel occupancy time (SICOT), a group-common physical downlink control channel (GC-PDCCH), or a common transmit preamble.
14. The wireless communication device of claim 12 , wherein monitoring for the signal indicating the COT is based on one of a CCA procedure or an extended CCA procedure performed on the first frequency sub-band.
15. The wireless communication device of claim 12 , wherein the interface is further configured to:
switch to another frequency sub-band of the sequence of frequency sub-bands after a quantity of unsuccessful CCA procedures are performed on the first frequency sub-band, the quantity of unsuccessful CCA procedures based at least in part on the maximum quantity of CCA procedures to be performed; or
output at least a portion of a series of data frames for transmission using configured grant (CG) resources after the quantity of unsuccessful extended CCA procedures are performed on the first frequency sub-band, the quantity of unsuccessful CCA procedures based at least in part on the maximum quantity of CCA procedures to be performed.
16. A method performed by an apparatus of an access network node, comprising:
transmitting a discovery reference signal (DRS) to at least one user equipment (UE), the DRS including an indication of one or more clear channel assessment (CCA) parameters and indicating a frequency hopping pattern including a sequence of frequency sub-bands, the one or more CCA parameters indicating an initial slot position associated with transmissions over at least a first a first frequency sub-band of the sequence of frequency sub-bands, a maximum quantity of CCA procedures to be performed when gaining access to one or more respective frequency sub-bands of the sequence of frequency sub-bands, or both; and
contending for channel access on a first frequency sub-band of the sequence of frequency sub-bands using a CCA procedure and based at least in part on the maximum quantity of CCA procedures to be performed.
17. The method of claim 16 , wherein transmitting the DRS comprises:
accessing an anchor channel of an unlicensed frequency band using the CCA procedure; and
transmitting the DRS over the anchor channel based on accessing the anchor channel.
18. The method of claim 16 , further comprising:
indicating a channel occupancy time (COT) obtained on the first frequency sub-band by transmitting one or more of system information channel occupancy time (SI-COT), a group-common physical downlink control channel (GC-PDCCH), or a common transmit preamble to the at least one UE.
19. The method of claim 16 , further comprising:
performing one or more unsuccessful CCA procedures comprising the CCA procedure within a time period that is associated with the maximum quantity of CCA procedures; and
receiving at least a portion of a series of data frames using configured grant (CG) resources based at least in part on performing the one or more unsuccessful CCA procedures within the time period, each data frame of the series of data frames being preceded by a corresponding DRS and is communicated over a corresponding frequency sub-band of the sequence of frequency sub-bands.
20. The method of claim 16 , further comprising:
contending for channel access on the first frequency sub-band using an extended CCA procedure based at least in part on not gaining channel access using the CCA procedure;
obtaining access to the first frequency sub-band based at least in part on the extended CCA procedure; and
communicating a first data frame of a series of data frames over the first frequency sub-band based on at least in part obtaining access to the first frequency sub-band.
21. The method of claim 20 , further comprising:
switching to another frequency sub-band of the sequence of frequency sub-bands after a quantity of unsuccessful CCA procedures, the quantity of unsuccessful CCA procedures based at least in part on the maximum quantity of CCA procedures to be performed.
22. The method of claim 16 , wherein the DRS includes enhanced remaining minimum system information (eRMSI) indicating the frequency hopping pattern and each of the frequency sub-bands.
23. The method of claim 16 , further comprising at least one of:
puncturing a first symbol of a first data frame of a series of data frames to facilitate a CCA procedure associated with transmission of the first data frame; or
puncturing a last symbol of the first data frame to facilitate a CCA procedure associated with transmission of a subsequent DRS.
24. The method of claim 16 , further comprising at least one of:
puncturing a first symbol of the DRS to facilitate the CCA procedure associated with transmission of the DRS; or
puncturing a last symbol of the DRS to facilitate a CCA procedure associated with transmission of a first data frame of a series of data frames.
25. A wireless communication device, comprising:
a memory;
at least one network interface; and
a processing system communicatively coupled to the memory and the at least one network interface, wherein the processing system is configured to:
transmit a discovery reference signal (DRS) to at least one user equipment (UE), the DRS including an indication of one or more clear channel assessment (CCA) parameters and indicating a frequency hopping pattern including a sequence of frequency sub-bands, the one or more CCA parameters indicating an initial slot position associated with transmissions over at least a first frequency sub-band of the sequence of frequency sub-bands, a maximum quantity of CCA procedures to be performed when gaining access to one or more respective frequency sub-bands of the sequence of frequency sub-bands, or both; and
contend for channel access on a first frequency sub-band of the sequence of frequency sub-bands using a CCA procedure and based at least in part on the maximum quantity of CCA procedures to be performed.
26. The wireless communication device of claim 25 , wherein the processing system is further configured to:
indicate a channel occupancy time (COT) obtained on the first frequency sub-band by transmitting one or more of system information channel occupancy time (SI-COT), a group-common physical downlink control channel (GC-PDCCH), or a common transmit preamble to the at least one UE.
27. The wireless communication device of claim 25 , wherein the processing system is further configured to:
contend for channel access on the first frequency sub-band using an extended CCA procedure based at least in part on not gaining channel access using the CCA procedure;
obtain access to the first frequency sub-band based at least in part on the extended CCA procedure; and
communicate a first data frame of a series of data frames over the first frequency sub-band based at least in part on obtaining access to the first frequency sub-band.
28. The wireless communication device of claim 27 , wherein the processing system is further configured to:
switch to another frequency sub-band of the sequence of frequency sub-bands after a quantity of unsuccessful CCA procedures, the quantity of unsuccessful CCA procedures based at least in part on the maximum quantity of CCA procedures to be performed.