TWO-STEP RANDOM ACCESS PROCEDURE IN NEXT GENERATION WIRELESS NETWORKS
Some of the present implementations provide a method for a base station (BS) for performing a random access (RA) procedure. The method includes transmitting, to a UE, a system information block (SIB) including a two-step RA configuration with a reference signal received power (RSRP) threshold, the SIB further indicating whether switching an RA procedure from a two-step type to a four-step type by the UE is allowed; and transmitting, to the UE, a four-step RA configuration, wherein: the UE determines whether a detected RSRP exceeds the received RSRP threshold once the RA procedure is triggered, and performs the RA procedure using the two-step type after determining that the detected RSRP exceeds the received RSRP threshold.
1 . A method for a base station (BS) for performing a random access (RA) procedure, the method comprising:
transmitting, to a user equipment (UE), a system information block (SIB) comprising a two-step RA configuration with a reference signal received power (RSRP) threshold, the SIB further indicating whether switching an RA procedure from a two-step type to a four-step type by the UE is allowed; and
transmitting, to the UE, a four-step RA configuration, wherein:
the UE determines whether a detected RSRP exceeds the received RSRP threshold once the RA procedure is triggered, and
performs the RA procedure using the two-step type after determining that the detected RSRP exceeds the received RSRP threshold.
2 . The method of claim 1 , wherein performing the RA procedure using the two-step type comprises:
setting a counter to one;
transmitting, to the BS, a first message in a first step of the RA procedure using the two-step type; and
iteratively performing the following steps while the RA procedure uses the two-step type and the RA procedure using the two-step type is not successful:
adding one to the counter,
when the SIB indicates that switching the RA procedure from the two-step type to the four-step type is allowed and the counter is less than a first threshold, transmitting another first message to the BS, and
in a case that the SIB indicates that switching the RA procedure from the two-step type to the four-step type is allowed and the counter is equal to the first threshold, switching the RA procedure from the two-step type to the four-step type.
3 . The method of claim 2 , wherein the iteratively performing the following steps further comprises:
when the SIB indicates that switching the RA procedure from the two-step type to the four-step type is not allowed and the counter is less than a second threshold, transmitting another first message to the BS, and
in a case that the SIB indicates that switching the RA procedure from the two-step type to the four-step type is not allowed and the counter is equal to the second threshold, declaring, to an upper layer of the UE, a failure of the RA procedure.
4 . The method of claim 2 , wherein performing the RA procedure using the two-step type further comprises:
determining, after transmitting the first message to the BS, whether a second message from the BS in a second step of the RA procedure using the two-step type is received successfully, wherein:
the first message comprises a preamble and a payload, and
the second message comprises at least one response including at least one of contention resolution information associated with the RA procedure using the two-step type and fallback information.
5 . The method of claim 4 , wherein the second message comprises a media access control (MAC) subheader of a MAC sub-Protocol Data Unit (subPDU) having at least one field that indicates whether the at least one response contains the contention resolution information associated with the RA procedure using the two-step type for indicating a successful RA procedure using the two-step type or the fallback information for transmitting a third message to the BS.
6 . The method of claim 4 , wherein determining whether the RA procedure using the two-step type is successful comprises:
determining that the RA procedure using the two-step type is not successful when the second message is not received successfully before an RA response time threshold has expired.
7 . The method of claim 4 , wherein the second message comprises a radio resource control (RRC) message that is a response message to an RRC procedure request indicated in the first message.
8 . A base station (BS), comprising:
one or more non-transitory computer-readable media storing one or more instructions for performing a random access (RA) procedure; and
at least one processor coupled to the one or more non-transitory computer-readable media, and configured to execute the one or more instructions to cause the BS to:
transmit, to a user equipment (UE), a system information block (SIB) comprising a two-step RA configuration with a reference signal received power (RSRP) threshold, the SIB further indicating whether switching from a two-step type to a four-step type by the UE is allowed; and
transmit, to the UE, a four-step RA configuration, wherein:
the UE determines whether a detected RSRP exceeds the received RSRP threshold once the RA procedure is triggered, and
performs the RA procedure using the two-step type after determining that the detected RSRP exceeds the received RSRP threshold.
9 . The BS of claim 8 , wherein performing the RA procedure using the two-step type comprises:
setting a counter to one;
transmitting, to the BS, a first message in a first step of the RA procedure using the two-step type; and
iteratively performing the following steps while the RA procedure uses the two-step type and the RA procedure using the two-step type is not successful:
adding one to the counter,
when the SIB indicates that switching the RA procedure from the two-step type to the four-step type is allowed and the counter is less than a first threshold, transmitting another first message to the BS, and
in a case that the SIB indicates that switching the RA procedure from the two-step type to the four-step type is allowed and the counter is equal to the first threshold, switching the RA procedure from the two-step type to the four-step type.
10 . The BS of claim 9 , wherein the iteratively performing the following steps further comprises:
when the SIB indicates that switching the RA procedure from the two-step type to the four-step type is not allowed and the counter is less than a second threshold, transmitting another first message to the BS, and
in a case that the SIB indicates that switching the RA procedure from the two-step type to the four-step type is not allowed and the counter is equal to the second threshold, declaring, to an upper layer of the UE, a failure of the RA procedure.
11 . The BS of claim 9 , wherein performing the RA procedure using the two-step type further comprises:
determining, after transmitting the first message to the BS, whether a second message from the BS in a second step of the RA procedure using the two-step type is received successfully, wherein:
the first message comprises a preamble and a payload, and
the second message comprises at least one response including at least one of contention resolution information associated with the RA procedure using the two-step type and fallback information.
12 . The BS of claim 11 , wherein the second message comprises a media access control (MAC) subheader of a MAC sub-Protocol Data Unit (subPDU) having at least one field that indicates whether the at least one response contains the contention resolution information associated with the RA procedure using the two-step type for indicating a successful RA procedure using the two-step type or the fallback information for transmitting a third message to the BS.
13 . The BS of claim 11 , wherein determining whether the RA procedure using the two-step type is successful comprises:
determining that the RA procedure using the two-step type is not successful when the second message is not received successfully before an RA response time threshold has expired.
14 . The BS of claim 11 , wherein the second message comprises a radio resource control (RRC) message that is a response message to an RRC procedure request indicated in the first mes sage.
15 . A method for a user equipment (UE) for performing a random access (RA) procedure, the method comprising:
receiving, from a base station (BS), a system information block (SIB) comprising a two-step RA configuration with a reference signal received power (RSRP) threshold, the SIB further indicating whether switching from a two-step type to a four-step type is allowed;
receiving, from the BS, a four-step RA configuration;
determining whether a detected RSRP exceeds the RSRP threshold once the RA procedure is triggered; and
performing the RA procedure using the two-step type after determining that the detected RSRP exceeds the received RSRP threshold.
16 . The method of claim 15 , wherein performing the RA procedure using the two-step type comprises:
setting a counter to one;
transmitting, to the BS, a first message in a first step of the RA procedure using the two-step type; and
iteratively performing the following steps while the RA procedure uses the two-step type and the RA procedure using the two-step type is not successful:
adding one to the counter,
when the SIB indicates that switching the RA procedure from the two-step type to the four-step type is allowed and the counter is less than a first threshold, transmitting another first message to the BS, and
in a case that the SIB indicates that switching the RA procedure from the two-step type to the four-step type is allowed and the counter is equal to the first threshold, switching the RA procedure from the two-step type to the four-step type.
17 . The method of claim 16 , wherein the iteratively performing the following steps further comprises:
when the SIB indicates that switching the RA procedure from the two-step type to the four-step type is not allowed and the counter is less than a second threshold, transmitting another first message to the BS, and
in a case that the SIB indicates that switching the RA procedure from the two-step type to the four-step type is not allowed and the counter is equal to the second threshold, declaring, to an upper layer of the UE, a failure of the RA procedure.
18 . The method of claim 16 , wherein performing the RA procedure using the two-step type further comprises:
determining, after transmitting the first message to the BS, whether a second message from the BS in a second step of the RA procedure using the two-step type is received successfully, wherein:
the first message comprises a preamble and a payload, and
the second message comprises at least one response including at least one of contention resolution information associated with the RA procedure using the two-step type and fallback information.
19 . The method of claim 18 , wherein the second message comprises a media access control (MAC) subheader of a MAC sub-Protocol Data Unit (subPDU) having at least one field that indicates whether the at least one response contains the contention resolution information associated with the RA procedure using the two-step type for indicating a successful RA procedure using the two-step type or the fallback information for transmitting a third message to the BS.
20 . The method of claim 18 , wherein determining whether the RA procedure using the two-step type is successful comprises:
determining that the RA procedure using the two-step type is not successful when the second message is not received successfully before an RA response time threshold has expired.