METHOD AND APPARATUS FOR LAYER 2 MOBILITY IN MOBILE WIRELESS COMMUNICATION SYSTEM
A method and apparatus for layer 2 mobility is provided. Method for lower layer mobility includes receiving a RRCReconfigruation from the base station, receiving a PDCCH order from the base station, transmitting a preamble based on the type2 PDCCH order for a first mobility group, receiving in a first cell a MAC CE for lower layer mobility execution toward the second mobility group, performing a first operation set in the first mobility group at a first point of time, performing a second operation set in the second mobility group at a second point of time and performing a third operation set in the second mobility group at a third point of time.
1 . A method by a terminal, the method comprising:
receiving, by the terminal from a base station, a radio resource control (RRC) reconfiguration message, wherein the RRC reconfiguration message comprises:
one or more embedded RRC reconfiguration messages, wherein each of the one or more embedded RRC reconfiguration messages is associated with a candidate cell; and
one or more first identifiers, wherein each of the one or more first identifiers is associated with one of the one or more embedded RRC reconfiguration messages;
performing, by the terminal and based on an embedded RRC reconfiguration message, a first set of operations for the candidate cell associated with the embedded RRC reconfiguration message, wherein the first set of operations comprises downlink synchronization;
receiving, by the terminal from the base station, a first downlink (DL) Medium Access Control (MAC) message, wherein the first DL MAC message comprises a first identifier field; and
transmitting, by the terminal to the base station, an uplink (UL) MAC message, wherein the UL MAC message comprises a Buffer Status Report (BSR),
wherein the BSR is triggered as a consequence of reception of the first DL MAC message.
2 . The method of claim 1 ,
wherein the BSR is triggered based on configuration parameters for BSR comprised in a specific embedded RRC message.
3 . The method of claim 2 ,
wherein the specific embedded RRC message is determined based on a value comprised in the first identifier field in the first DL MAC message.
4 . The method of claim 1 ,
wherein the UL MAC message further comprises a Power Headroom Report (PHR).
5 . The method of claim 4 ,
wherein the PHR is triggered based on configuration parameters for PHR comprised in a specific embedded RRC message.
6 . The method of claim 4 ,
wherein a format of the PHR is determined based on the configuration parameters for PHR comprised in the specific embedded RRC message.
7 . The method of claim 6 ,
wherein the specific embedded RRC message is determined based on a value comprised in the first identifier field in the first DL MAC message.
8 . The method of claim 1 , further comprising:
receiving, by the terminal from the base station, a second DL MAC message, wherein the second DL MAC message comprises the first identifier field; and
canceling, by the terminal, BSR triggered based on configuration parameters for BSR comprised in a specific embedded RRC reconfiguration message in case that a value in the first identifier field of the second DL MAC message and a value in the first identifier field of the first DL MAC message are different from each other,
wherein the BSR is cancelled as a consequence of reception of the second DL MAC CE.
9 . The method of claim 8 ,
wherein the specific embedded RRC reconfiguration message is determined based on a value comprised in the first identifier field in the first DL MAC message.
10 . The method of claim 8 , further comprising:
canceling, by the terminal, PHR triggered based on configuration parameters for PHR comprised in a specific embedded RRC reconfiguration message in case that a value in the first identifier field of the second DL MAC message and a value in the first identifier field of the first DL MAC message are different from each other,
wherein the PHR is cancelled as a consequence of reception of the second MAC CE.
11 . The method of claim 10 ,
wherein the specific embedded RRC message is determined based on a value comprised in the first identifier field in the first DL MAC message.
12 . The method of claim 1 ,
wherein the first set of operations further comprises measuring a Synchronization Signal/Physical Broadcast Channel (SSB) of the candidate cell based on a parameter indicating an absolute frequency of the SSB, and wherein the parameter is comprised in the embedded RRC reconfiguration message associated with the candidate cell.
13 . The method of claim 12 ,
wherein the first set of operations further comprises determining a pathloss of the SSB of the candidate cell based on the measuring the SSB.
14 . The method of claim 1 ,
wherein the first set of operations further comprises receiving Master Information Block (MIB) of the candidate cell based on one or more parameters comprised in the embedded RRC reconfiguration message associated with the candidate cell.
15 . The method of claim 14 ,
wherein the one or more parameters comprised in the embedded RRC reconfiguration message associated with the candidate cell comprises:
a parameter indicating a Synchronization Signal/Physical Broadcast Channel (SSB) position in burst; and
a parameter indicating an absolute frequency of SSB.
16 . The method of claim 1 , further comprising:
performing uplink resource release before the BSR is triggered and after the first DL MAC CE is received.
17 . The method of claim 16 ,
wherein the uplink resource comprises a configured uplink grant.
18 . The method of claim 16 ,
wherein the uplink resource further comprises Physical Uplink Control Channel (PUCCH) and Sounding Reference Signal (SRS).
19 . The method of claim 1 , further comprising:
stopping an ongoing random access procedure before the BSR is triggered and after the first MAC CE is received.
20 . A terminal comprising:
a transceiver,
a memory, and
a controller coupled to the transceiver and the memory, wherein the controller is configured to cause the terminal to:
receive, from a base station, a radio resource control (RRC) reconfiguration message, wherein the RRC reconfiguration message comprises:
one or more embedded RRC reconfiguration messages, wherein each of the one or more embedded RRC reconfiguration messages is associated with a candidate cell; and
one or more first identifiers, wherein each of the one or more first identifiers is associated with one of the one or more embedded RRC reconfiguration messages;
perform, based on an embedded RRC reconfiguration message, a first set of operations for the candidate cell associated with the embedded RRC reconfiguration message, wherein the first set of operations comprises downlink synchronization;
receive, from the base station, a first downlink (DL) Medium Access Control (MAC) message, wherein the first DL MAC message comprises a first identifier field; and
transmit, to the base station, an uplink (UL) MAC message, wherein the UL MAC message comprises a Buffer Status Report (BSR),
wherein the BSR is triggered as a consequence of reception of the first DL MAC message.