Method and apparatus for random access layered preambles

1. An operation method of a terminal in a communication system, the operation method comprising:

receiving, from a base station, quality of service (QoS) information for preamble groups and information on preambles belonging to each of the preamble groups;

selecting one preamble group from among the preamble groups based on the QoS information and a QoS of the terminal;

selecting a preamble within the one preamble group based on the information on preambles belonging to each of the preamble groups;

transmitting a first message including the selected preamble to the base station; and

receiving, from the base station, a second message that is a response to the first message,

wherein the preamble groups include a first preamble group for first-type terminals whose required latency is less than a threshold and a second preamble group for second-type terminals whose required latency is equal to or greater than the threshold.

2. The operation method according to claim 1 , wherein the preamble groups include the first preamble group and the second preamble group generated by dividing an original preamble group consisting of constant amplitude zero autocorrelation (CAZAC) sequences having a prime sequence length based on cross-correlation, and a cross-correlation of preambles belonging to the first preamble group is smaller than a cross-correlation of preambles belonging to the second preamble group.

3. The operation method according to claim 2 , wherein the CAZAC sequence is a Zadoff-Chu sequence, and the prime sequence length is one of 389 and 139.

4. The operation method according to claim 1 , further comprising receiving information on transmit powers for the preamble groups, wherein the selected preamble is transmitted using a transmit power according to the information on the transmit powers.

5. The operation method according to claim 1 , wherein a transmit power for the first preamble group is greater than a transmit power for the second preamble group.

6. The operation method according to claim 1 , further comprising receiving, from the base station, configuration information of a random access channel (RACH) occasion bundle and a number of RACH occasions included in the RACH occasion bundle, wherein the selected preamble is transmitted in a RACH occasion indicated by the configuration information.

7. The operation method according to claim 1 , wherein the first message is MsgA and the second message is MsgB.

8. An operation method of a base station in a communication system, the operation method comprising:

configuring preamble groups, preambles belonging to each of the preamble groups, and a QoS of each of the preamble groups;

transmitting preamble group configuration information to a terminal, the preamble group configuration information including information on the preamble groups, information on the preambles belonging to each of the preamble groups, and QoS information on the QoS of each of the preamble groups;

receiving, from the terminal, a first message including a preamble selected based on the preamble group configuration information and a QoS of the terminal;

detecting the preamble in the first message; and

transmitting, to the terminal, a second message that is a response to the first message,

wherein the preamble groups include a first preamble group for first-type terminals whose required latency is less than a threshold and a second preamble group for second-type terminals whose required latency is equal to or greater than the threshold.

9. The operation method according to claim 8 , wherein the configuring comprises:

generating an original preamble group having constant amplitude zero autocorrelation (CAZAC) sequences having a prime sequence length as member preambles;

allocating the preambles in the original preamble group as the preambles belonging to the preamble groups; and

configuring the QoS for each of the preamble groups.

10. The operation method according to claim 9 , wherein the allocating of the preambles comprises:

excluding preambles having a cross-correlation greater than or equal to a first threshold from the original preamble group;

calculating cross-correlations of preambles remaining in the original preamble group; and

allocating the remaining preambles to the preamble groups based on the calculated cross-correlations.

11. The operation method according to claim 9 , wherein the configuring of the QoS for each of the preamble groups comprises:

configuring QoS levels according to various QoS thresholds; and

mapping the QoS level to each of the preamble groups.

12. The operation method according to claim 9 , wherein the configuring of the QoS for each of the preamble groups comprises configuring the QoS for each of the preamble groups by using a QoS specifier(s) indicating a preamble group(s) that the base station is able to select.

13. The operation method according to claim 8 , wherein the detecting of the preamble in the first message comprises:

calculating cross-correlations by applying a preamble matrix of one preamble group to a received signal matrix of the first messages received from a plurality of terminals including the terminal;

detecting preambles belonging to the one preamble group using the calculated cross-correlations;

removing received signals corresponding to the detected preambles from the received signal matrix; and

detecting the preamble in the first message by detecting preambles belonging to the remaining preamble groups in the received signal matrix from which the received signals are removed.

14. A terminal, the terminal comprising a processor, a memory electronically communicating with the processor, and instructions stored in the memory, wherein when executed by the processor, the instructions cause the terminal to:

receive, from a base station, quality of service (QoS) information for preamble groups and information on preambles belonging to each of the preamble groups;

select one preamble group from among the preamble groups based on the QoS information and a QoS of the terminal;

select a preamble within the one preamble group based on the information on preambles belonging to each of the preamble groups;

transmit a first message including the selected preamble to the base station; and

receive, from the base station, a second message that is a response to the first message,

wherein the preamble groups include a first preamble group for first-type terminals whose required latency is less than a threshold and a second preamble group for second-type terminals whose required latency is equal to or greater than the threshold.

15. The terminal according to claim 14 , wherein the preamble groups include the first preamble group and the second preamble group generated by dividing an original preamble group consisting of constant amplitude zero autocorrelation (CAZAC) sequences having a prime sequence length based on cross-correlation, and a cross-correlation of preambles belonging to the first preamble group is smaller than a cross-correlation of preambles belonging to the second preamble group.

16. The terminal according to claim 14 , wherein the instructions further cause the terminal to receive information on transmit powers for the preamble groups, wherein the selected preamble is transmitted using a transmit power according to the information on the transmit powers.

17. The terminal according to claim 14 , wherein the instructions further cause the terminal to receive, from the base station, configuration information of a random access channel (RACH) occasion bundle and a number of RACH occasions included in the RACH occasion bundle, wherein the selected preamble is transmitted in a RACH occasion indicated by the configuration information.