Methods, apparatuses and systems directed to network access for non-terrestrial networks
Methods, apparatuses, systems, etc. for, and/or for use in connection with, performing initial access in a non-terrestrial network (NTN) of a communications system. Among such methods is a method that may be implemented in a wireless transmit/receive unit (WTRU) and may include any of receiving, from the NTN, differential delay information and physical random access channel (PRACH) configuration information indicating a set of preambles and a PRACH occasions configuration; determining a set of candidate PRACH occasions, from among a plurality of PRACH occasions of the PRACH occasion configuration, based on the differential delay information; selecting a preamble from a group of the preambles allocated to one candidate PRACH occasion of the set of candidate PRACH occasions; and transmitting the selected preamble using a PRACH resource corresponding to the one candidate PRACH occasion.
1. A method implemented in a wireless transmit/receive unit (WTRU), the method comprising:
receiving, from a network element of a network including a non-terrestrial network, differential delay information and physical random access channel (PRACH) configuration information indicating a plurality of preambles and a PRACH occasion configuration;
determining a set of candidate PRACH occasions, from among a plurality of PRACH occasions of the PRACH occasion configuration, based on the differential delay information;
selecting a preamble from a group of preambles of the plurality of preambles, wherein the group of preambles is allocated to one candidate PRACH occasion of the set of candidate PRACH occasions; and
transmitting the selected preamble using a PRACH resource corresponding to the one candidate PRACH occasion.
2. The method of claim 1 , wherein the differential delay information comprises a maximum delay difference.
3. The method of claim 1 , comprising:
determining a delay difference period based on the differential delay information, wherein determining the set of candidate PRACH occasions comprises:
determining, from among the plurality of PRACH occasions of the PRACH occasion configuration, the set of candidate PRACH occasions that are within one delay difference period.
4. The method of claim 3 , comprising determining a number of groups of preambles of the plurality of preambles based on a number of PRACH resources within the delay difference period.
5. The method of claim 1 , comprising:
allocating the group of preambles to the one candidate PRACH occasion.
6. The method of claim 1 , comprising one of:
allocating the group of preambles to the one candidate PRACH occasion based on a rule, wherein the rule specifies that one partition of the plurality of preambles is to be allocated; and
allocating the group of preambles to the one candidate PRACH occasion based on a configured mapping.
7. The method of claim 1 , comprising:
selecting the one candidate PRACH occasion from among the set of candidate PRACH occasions.
8. The method of claim 1 , comprising one of:
determining the one candidate PRACH occasion from among the set of candidate PRACH occasions based on the group of the preambles allocated to one candidate PRACH occasion including a preamble having a particular characteristic;
determining the one candidate PRACH occasion from among the set of candidate PRACH occasions based on the group of preambles allocated to one candidate PRACH occasion lacking a preamble having the particular characteristic; and
determining the one candidate PRACH occasion from among the set of candidate PRACH occasions based on the group of preambles allocated to one candidate PRACH occasion corresponding to a range of timing advances between the WTRU and the network.
9. The method of claim 1 , comprising selecting at least one frequency resource to transmit the selected preamble.
10. The method of claim 9 , wherein transmitting the selected preamble using a PRACH resource comprises transmitting the selected preamble based on frequency hopping configured by the network.
11. A wireless transmit/receive unit (WTRU) comprising circuitry, including any of a transmitter, receiver, processor and memory, configured to:
receive, from a network element of a network including a non-terrestrial network, differential delay information and physical random access channel (PRACH) configuration information indicating a plurality of preambles and a PRACH occasion configuration;
determine a set of candidate PRACH occasions, from among a plurality of PRACH occasions of the PRACH occasion configuration, based on the differential delay information;
select a preamble from a group of preambles of the plurality of preambles, wherein the group of preambles is allocated to one candidate PRACH occasion of the set of candidate PRACH occasions; and
transmit the selected preamble using a PRACH resource corresponding to the one candidate PRACH occasion.
12. The WTRU of claim 11 , wherein the differential delay information comprises a maximum delay difference.
13. The WTRU of claim 11 , wherein the circuitry is configured to:
determine a delay difference period based on the differential delay information, wherein the circuitry being configured to determine the set of candidate PRACH occasions comprises the circuitry being configured to:
determine, from among the plurality of PRACH occasions of the PRACH occasion configuration, the set of candidate PRACH occasions that are within one delay difference period.
14. The WTRU of claim 13 , wherein the circuitry is configured to determine a number of groups of preambles of the plurality of preambles based on a number of PRACH resources within the delay difference period.
15. The WTRU of claim 11 , wherein the circuitry is configured to:
allocate the group of preambles to the one candidate PRACH occasion.
16. The WTRU of claim 11 , wherein the circuitry is configured to allocate the group of preambles to the one candidate PRACH occasion based on at least one of:
a rule, wherein the rule specifies that one partition of the plurality of preambles is to be allocated; and
a configured mapping.
17. The WTRU of claim 11 , wherein the circuitry is configured to:
select the one candidate PRACH occasion from among the set of candidate PRACH occasions.
18. The WTRU of claim 11 , wherein the circuitry is configured to determine the one candidate PRACH occasion from among the set of candidate PRACH occasions based on one of:
the group of preambles allocated to one candidate PRACH occasion including a preamble having a particular characteristic;
the group of preambles allocated to one candidate PRACH occasion lacking a preamble having the particular characteristic; and
the group of preambles allocated to one candidate PRACH occasion corresponding to a range of timing advances between the WTRU and the network.
19. The WTRU of claim 11 , wherein the circuitry is configured to select at least one frequency resource to transmit the selected preamble.
20. The WTRU of claim 19 , wherein the circuitry being configured to transmit the selected preamble using a PRACH resource comprises the circuitry being configured to transmit the selected preamble based on frequency hopping configured by the network.