Systems and method for selecting carrier resources for narrowband physical random access channel procedures
A Narrowband-Internet-of-Things (NB-IoT) device may select between multiple carrier resources (of an anchor carrier and/or non-anchor carriers) to perform a Narrowband Physical Random Access Channel (NPRACH) procedure. The NB-IoT device may determine, based on a reference signal from an enhanced NodeB (eNB), a coverage level for the NB-IoT device and receive carrier configuration information, from the eNB, that indicates the carriers (e.g., an anchor carrier and one or more non-anchor carriers) that are available for NPRACH procedure. The NB-IoT device may select a carrier resource from among the carriers based on factors, such as the coverage level of the NB-IoT device and the Reference Signals Received Power (RSRP) thresholds and Repetition levels of the carrier resources. The NB-IoT device may use the selected carrier resource to initiate the NPRACH procedure.
1. A Narrowband-Internet-of-Things (NB-IoT) device, comprising:
a radio frequency (RF) interface to RF circuitry; and
one or more processors to:
receive, via the RF interface, Reference Signal Received Power (RSRP) thresholds for a plurality of Physical Random Access Channel (PRACH) resources of one or more carriers;
receive, via the RF interface, selection probabilities for selecting a PRACH resource of an anchor carrier or a PRACH resource of a non-anchor carrier of one or more non-anchor carriers;
determine, based on a reference signal, received via the RF circuitry, a coverage level of the NB-IoT device;
map the coverage level of the NB-IoT device to the PRACH resources based on the coverage level of the NB-IoT device and the RSRP thresholds; and
when the coverage level of the NB-IoT device maps to multiple PRACH resources,
randomly select the PRACH resource, based on the selection probabilities, from the multiple PRACH resources, to perform a PRACH procedure.
2. The NB-IoT device of claim 1 , wherein the one or more carriers includes the anchor carrier and the one or more non-anchor carriers.
3. The NB-IoT device of claim 1 , wherein the selection probabilities include:
a first selection probability for selecting a PRACH resource from the anchor carrier or a PRACH resource of a non-anchor carrier of the one or more non-anchor carriers, and
a second selection probability for selecting a PRACH resource from the one or more non-anchor carriers.
4. The NB-IoT device of claim 3 , wherein the second selection probability is equal to:
one (1) minus the first selection probability, divided by a quantity of the multiple PRACH resources.
5. The NB-IoT device of claim 1 , wherein the RSRP thresholds are provided in one or more System Information Blocks.
6. The NB-IoT device of claim 1 , wherein the one or more processors is to:
receive an Uplink (UL) carrier index that indicates that the one or more carriers include the anchor carrier and the one or more non-anchor carriers.
7. The NB-IoT device of claim 1 , wherein the RSRP thresholds are received via a Physical Downlink Control Channel (PDCCH).
8. The NB-IoT device of claim 1 , wherein the one or more processors is to:
select a carrier, corresponding to the PRACH resource, to receive a Msg2 of the PRACH procedure;
select the carrier to communicate a Msg3 of the PRACH procedure; and
select the carrier where Msg2 is received to receive a Msg4 or Msg3 retransmission of the PRACH procedure.
9. A computer-readable medium containing program instructions for causing one or more processors, associated with Narrowband-Internet-of-Things (NB-IoT) device, to:
receive Reference Signal Received Power (RSRP) thresholds for a plurality of Physical Random Access Channel (PRACH) resources of one or more carriers;
receive selection probabilities for selecting a PRACH resource of an anchor carrier or a PRACH resource of a non-anchor carrier of one or more non-anchor carriers;
determine, based on a reference signal, a coverage level of the NB-IoT device;
map the coverage level of the NB-IoT device to the PRACH resources based on the coverage level of the NB-IoT device and the RSRP thresholds; and
when the coverage level of the NB-IoT device maps to multiple PRACH resources,
randomly select the PRACH resource, based on the selection probabilities, from the multiple PRACH resources, to perform a PRACH procedure.
10. The computer-readable medium of claim 9 , wherein the one or more carriers includes the anchor carrier and the one or more non-anchor carriers.
11. The computer-readable medium of claim 9 , wherein the selection probabilities include:
a first selection probability for selecting a PRACH resource from the anchor carrier or a PRACH resource of a non-anchor carrier of the one or more non-anchor carriers, and
a second selection probability for selecting a PRACH resource from the one or more non-anchor carriers.
12. The computer-readable medium of claim 11 , wherein the second selection probability is equal to:
one (1) minus the first selection probability, divided by a quantity of the multiple PRACH resources.
13. An apparatus for a baseband processor of Narrowband-Internet-of-Things (NB-IoT) device configured to:
receive selection probabilities for selecting between a Physical Random Access Channel (PRACH) carrier resource of an anchor carrier and a PRACH carrier resource of one or more non-anchor carriers;
map the NB-IoT device to one or more PRACH carrier resources, of a plurality of carriers, based on a coverage level of the NB-IoT device and Reference Signal Received Power (RSRP) thresholds of the PRACH carrier resources;
determine, based on the selection probabilities, a probability for selecting a PRACH carrier resource of the anchor carrier and probabilities for selecting each PRACH carrier resource of the one or more non-anchor carriers, and
when the coverage level of the NB-IoT device maps to multiple PRACH carrier resources,
randomly select the PRACH carrier resource, based on the selection probabilities, from the multiple PRACH carrier resources, to perform a PRACH procedure.
14. The apparatus of claim 13 , wherein the multiple PRACH carrier resources comprise the anchor carrier and the one or more non-anchor carriers.
15. The apparatus of claim 13 , wherein:
the probability for selecting the PRACH carrier resource of the anchor carrier is equal to a first selection probability, and
the probabilities for selecting each PRACH carrier resource is equal to: one (1) minus the first selection probability, divided by a quantity of the multiple PRACH resources.
16. The apparatus of claim 13 , wherein the one or more processors are to:
receive an Uplink (UL) carrier index that indicates that the multiple PRACH carrier resources comprise the anchor carrier and the one or more non-anchor carriers.
17. The apparatus of claim 13 , wherein the one or more processors is to:
select a carrier, corresponding to the PRACH resource, to receive a Msg2 of the PRACH procedure;
select the carrier to communicate a Msg3 of the PRACH procedure; and
select the carrier where Msg2 is received to receive a Msg4 or Msg3 retransmission of the PRACH procedure.
18. A base station, the base station comprising:
a radio frequency (RF) interface to RF circuitry; and
one or more processors to:
communicate, via the RF interface, Reference Signal Received Power (RSRP) thresholds for a plurality of Physical Random Access Channel (PRACH) resources of one or more carriers;
communicate, via the RF interface, selection probabilities for selecting a PRACH resource of an anchor carrier or a PRACH resource of a non-anchor carrier of one or more non-anchor carriers; and
when a coverage level, associated with a Narrowband-Internet-of-Things (NB-IoT) device and the base station, corresponds to multiple PRACH resources, perform a PRACH procedure based on PRACH resources randomly selected, based on the selection probabilities, by the NB-IoT device.
19. The base station of claim 18 , wherein the one or more carriers includes the anchor carrier and the one or more non-anchor carriers.
20. The base station of claim 18 , wherein the selection probabilities include:
a first selection probability for selecting a PRACH resource from the anchor carrier or a PRACH resource of a non-anchor carrier of the one or more non-anchor carriers, and
a second selection probability for selecting a PRACH resource from the one or more non-anchor carriers.
21. The base station of claim 20 , wherein the second selection probability is equal to:
one (1) minus the first selection probability, divided by a quantity of the multiple PRACH resources.
22. The base station of claim 18 , wherein the RSRP thresholds are provided in one or more System Information Blocks.
23. The apparatus of claim 18 , wherein the one or more processors is to:
communicate an Uplink (UL) carrier index that indicates that the one or more carriers include the anchor carrier and the one or more non-anchor carriers.
24. The base station of claim 18 , wherein the RSRP thresholds are communicated via a Physical Downlink Control Channel (PDCCH).
25. The base station of claim 18 , wherein the one or more processors is to:
select a carrier, corresponding to the PRACH resource, to communicate a Msg2 of the PRACH procedure;
receive, via the carrier, a Msg3 of the PRACH procedure; and
select the carrier, where Msg2 is received, to receive a Msg4 or Msg3 retransmission of the PRACH procedure.