Apparatus and method for determining beam in wireless communication system

1. A method for operating a terminal in a wireless communication system, comprising:

receiving, from a first base station (BS), each of reference signal sets via each of receive (Rx) beam groups of the terminal, wherein each of the reference signal sets is transmitted via each of transmit (Tx) beam groups of the first BS;

transmitting, to the first BS, information regarding measurement on the reference signal sets; and

receiving, from the first BS, each of reference signals of a first set identified among the reference signal sets based on the information,

wherein each of the beam groups is a bundle of beams for beamforming a reference signal set transmitted or received at the same time,

wherein each of the reference signals of the first set is transmitted via each of Tx beams of a Tx beam group identified among the Tx beam groups of the first BS, based on the information, and

wherein each of the reference signals of the first set is received via each of Rx beams of a Rx beam group identified among the Rx beam groups of the terminal, based on the information.

2. The method of claim 1 , further comprising:

transmitting, to the first BS, feedback information for indicating at least one Tx beam,

wherein the at least one Tx beam is identified among the Tx beams of the Tx beam group based on a channel quality for each of the reference signals of the first set.

3. The method of claim 1 , further comprising:

determining a channel quality for beam group pairs for each of the Tx beam groups and each of Rx beam groups; and

determining a beam group pair among the beam group pairs based on the determined channel quality,

wherein the Tx beam group and the Rx beam group belong to the determined beam group pair having best channel quality among the beam group pairs, and

wherein the determined beam group pair corresponds to the first set among the reference signal sets.

4. The method of claim 3 , wherein the Tx beam group comprises composite beams, and

wherein each of the composite beams comprises a first Tx beam used by the first BS and a second Tx beam used by a second BS.

5. The method of claim 3 , further comprising

determining channel quality for beam pairs of each of the Tx beams for the Tx beam group and each of the Rx beams for the Rx beam group; and

determining a beam pair among the beam pairs based on the determined channel quality,

wherein the Tx beam group and the Rx beam group correspond to the first set.

6. The method of claim 4 , wherein a first coverage of the first Tx beam and a second coverage of the second Tx beam are at least partly overlapped.

7. The method of claim 4 , further comprising:

if a channel quality deviation for the first Tx beam and the second Tx beam is equal to or smaller than a threshold, operating in a mode where the first BS and the second BS perform a cooperative transmission based on a composite beam comprising the first Tx beam and the second Tx beam.

8. The method of claim 4 , further comprising:

if a statistical channel quality for a composite beam is equal to or smaller than a threshold, operating in a mode where the first BS and the second BS perform an individual transmission based on an individual Tx beam.

9. The method of claim 3 , further comprising:

receiving, from a second BS, second reference signal sets being transmitted via second Tx beam groups comprising second Tx beams of the second BS;

comparing channel quality for each of the reference signal sets and each of the second reference signal sets;

transmitting, to the first BS, information regarding the compared channel quality;

receiving a message for indicating handover to the second BS based on the information; and

performing handover to the second BS based on a second beam group pair,

wherein the second beam group pair corresponds to a second Tx beam group of the second Tx beam groups.

10. The method of claim 3 , wherein the Tx beams included in the Tx beam group comprises at least one Tx beam being not adjacent each other, and

wherein the Rx beams included in the Rx beam group comprises at least one Rx beam being not adjacent each other.

11. A method for operating a first base station (BS) in a wireless communication system, comprising:

transmitting, to a terminal, each of reference signal sets via each of transmit (Tx) beam groups of the first BS, wherein each of the reference signal sets is received via each of receive (Rx) beam groups of the terminal;

receiving, from the terminal, information regarding measurement on the reference signal sets; and

transmitting, to the terminal, each of reference signals of a first set identified among the reference signal sets based on the information,

wherein each of the beam groups is a bundle of beams for beamforming a reference signal set transmitted or received at the same time,

wherein each of the reference signals of the first set is transmitted via each of Tx beams of a Tx beam group identified among the Tx beam groups of the first BS, based on the information, and

wherein each of the reference signals of the first set is received via each of Rx beams of a Rx beam group identified among the Rx beam group of the terminal, based on the information.

12. The method of claim 11 , further comprising:

receiving, from the terminal, feedback information for indicating at least one Tx beam,

wherein the at least one Tx beam is identified among the Tx beams of the Tx beam group based on a channel quality for each of the reference signals of the first set.

13. The method of claim 11 , wherein the Tx beam group comprises composite beams, and

wherein each of the composite beams comprises a first Tx beam used by the first BS and a second Tx beam used by a second BS.

14. The method of claim 13 , wherein a first coverage of the first Tx beam and a second coverage of the second Tx beam are at least partly overlapped.

15. The method of claim 11 , wherein the Tx beam group and the Rx beam group belong to a beam group pair having a best channel quality among beam group pairs of each of the Tx beam groups and each of the Rx beam groups, and

wherein the beam group pair corresponds to the first set among the reference signal sets.

16. The method of claim 13 , further comprising:

if a channel quality deviation for the first Tx beam and the second Tx beam is equal to or smaller than a threshold, operating in a mode where the first BS and the second BS perform a cooperative transmission based on a composite beam comprising the first Tx beam and the second Tx beam.

17. The method of claim 13 , further comprising:

if a statistical channel quality for a composite beam is equal to or smaller than a threshold, operating in a mode where the first BS and the second BS perform an individual transmission based on an individual Tx beam.

18. The method of claim 13 , further comprising:

receiving, from the terminal, information regarding channel quality for each of the reference signal sets and each of second reference signal sets; and

transmitting, to the terminal, a message indicating to perform handover based on the information,

wherein a beam group pair comprising the first TX beam and the second TX beam corresponds to the first set among the reference signal sets, and

wherein each of the second reference signal sets is transmitted from the second BS to the terminal.

19. The method of claim 11 , wherein the Tx beams included in the Tx beam group comprises at least one Tx beam being not adjacent each other, and

wherein the Rx beams included in the Rx beam group comprises at least one Rx beam being not adjacent each other.

20. An apparatus for a terminal in a wireless communication system, comprising:

a transceiver; and

at least one processor, operatively connected to the transceiver, configured to:

receive, from a first base station (BS), each of reference signal sets being transmitted via each of transmit (Tx) beam groups of the first BS, wherein each of the reference signal sets is received via each of receive (Rx) beam groups of the terminal,

transmit, to the first BS, information regarding measurement on the reference signal sets, and

receive from the first BS, each of reference signals of a first set identified among the reference signal sets based on the information,

wherein each of the beam groups is a bundle of beams for beamforming a reference signal set transmitted or received at the same time,

wherein each of reference signals of the first set is transmitted via each of Tx beams of a Tx beam group identified among the Tx beam groups of the first BS, based on the information, and

wherein each of reference signals of the first set is received via each of Rx beams of a Rx beam group identified among the Rx beam groups of the terminal, based on the information.

21. The apparatus of claim 19 , wherein the at least one processor is further configured to transmit, to the first BS, feedback information for indicating at least one Tx beam, and

wherein the at least one Tx beam is identified among the Tx beams of the Tx beam group based on a channel quality for each of the reference signals of the first set.

22. The apparatus of claim 19 , wherein the at least one processor is further configured to:

determine channel quality for beam group pairs of each of the Tx beam groups and each of Rx beam groups; and

determine a beam group pair among the beam group pairs based on the determined channel quality,

wherein the Tx beam group and the Rx beam group belong to the determined beam group pair having best channel quality among the beam group pairs, and

wherein the determined beam group pair corresponds to the first set among the reference signal sets.

23. The apparatus of claim 21 , wherein the Tx beam group comprises composite beams, and

wherein each of the composite beams comprises a first Tx beam used by the first BS and a second Tx beam used by a second BS.

24. The apparatus of claim 21 , wherein the at least one processor is further configured to:

determine channel quality for beam pairs of each of the Tx beams for the Tx beam group and each of the Rx beams for the Rx beam group; and

determine a beam pair among the beam pairs based on the determined channel quality, and

wherein the Tx beam group and the Rx beam group correspond to the first set.

25. The apparatus of claim 23 , wherein a first coverage of the first Tx beam and a second coverage of the second Tx beam are at least partly overlapped.

26. The apparatus of claim 23 , wherein the at least one processor is further configured to:

if a channel quality deviation for the first Tx beam and the second Tx beam is equal to or smaller than a threshold, operate in a mode where the first BS and the second BS perform a cooperative transmission based on a composite beam comprising the first Tx beam and the second Tx beam.

27. The apparatus of claim 23 , wherein the at least one processor is further configured to:

if a statistical channel quality for a composite beam is equal to or smaller than a threshold, operate in a mode where the first BS and the second BS perform an individual transmission based on an individual Tx beam.

28. The apparatus of claim 20 , wherein the at least one processor is further configured to:

receive, from a second BS, second reference signal sets being transmitted via second Tx beam groups comprising second Tx beams of the second BS;

compare channel quality for each of the reference signal sets and each of the second reference signal sets;

transmit, to the first BS, information regarding the compared channel quality;

receive a message for indicating handover to the second BS based on the information; and

perform handover to the second BS based on a second beam group pair, and

wherein the second beam group pair corresponds to a second Tx beam group of the second Tx beam groups.

29. The apparatus of claim 21 , wherein the Tx beams included in the Tx beam group comprises at least one Tx beam being not adjacent each other, and

wherein the Rx beams included in the Rx beam group comprises at least one Rx beam being not adjacent each other.

30. An apparatus for a first base station (BS) in a wireless communication system, comprising:

a transceiver; and

at least one processor, operatively connected to the transceiver, configured to:

transmit, to a terminal, each of reference signal sets via each of transmit (Tx) beam groups of the first BS, wherein each of the reference signal sets are received via each of receive (Rx) beam groups of the terminal,

receive, from the terminal, information regarding measurement on the reference signal sets, and

transmit, to the terminal, each of reference signals of a first set identified among the reference signal sets based on the information,

wherein each of the beam groups is a bundle of beams for beamforming a reference signal set transmitted or received at the same time,

wherein each of the reference signals of the first set is transmitted via each of Tx beams of a Tx beam group identified among the Tx beam groups of the first BS, based on the information, and

wherein the each of the reference signals of the first set is received via each of Rx beams of a Rx beam group identified among the Rx beam group of the terminal, based on the information.

31. The apparatus of claim 30 , wherein the at least one processor is further configured to:

receive, from the terminal, feedback information for indicating at least one Tx beam,

wherein the at least one Tx beam is identified among the Tx beams of the Tx beam group based on a channel quality for each of the reference signals of the first set.

32. The apparatus of claim 31 , wherein the Tx beam group comprises composite beams, and

wherein each of the composite beams comprises a first Tx beam used by the first BS and a second Tx beam used by a second BS.

33. The apparatus of claim 32 , wherein a first coverage of the first Tx beam and a second coverage of the second Tx beam are at least partly overlapped.

34. The apparatus of claim 30 , wherein the Tx beam group and the Rx beam group belong to a beam group pair having a best channel quality among beam group pairs of each of the Tx beam groups and each of the Rx beam groups, and

wherein the beam group pair corresponds to the first set among the reference signal sets.

35. The apparatus of claim 32 , wherein the at least one processor is further configured to:

if a channel quality deviation for the first Tx beam and the second Tx beam is equal to or smaller than a threshold, operate in a mode where the first BS and the second BS perform a cooperative transmission based on a composite beam comprising the first Tx beam and the second Tx beam.

36. The apparatus of claim 32 , wherein the at least one processor is further configured to:

if a statistical channel quality for a composite beam is equal to or smaller than a threshold, operate in a mode where the first BS and the second BS perform an individual transmission based on an individual Tx beam.

37. The apparatus of claim 30 , wherein the at least one processor is further configured to:

receive, from the terminal, information regarding channel quality for each of the reference signal sets and each of second reference signal sets, and

transmit, to the terminal, a message indicating to perform handover based on the information,

wherein a beam group pair comprising a first TX beam and a second TX beam corresponds to the first set among the reference signal sets, and

wherein each of the second reference signal sets is transmitted from a second BS to the terminal.

38. The apparatus of claim 31 , wherein the Tx beams included in the Tx beam group comprises at least one Tx beam being not adjacent each other, and

wherein the Rx beams included in the Rx beam group comprises at least one Rx beam being not adjacent each other.