Communication system with beam quality measurement
A method, performed by a communication device, including a) measuring a respective beam quality for each of a plurality of beams of a cell, b) identifying, within said plurality of beams, a first group of beams comprising a number, N, of beams, c) selecting, from within said first group of beams, a second group of beams comprising a number, M, of beams, and d) deriving a cell quality for the cell based on the measured beam qualities for the M beams of the second group.
1. A method, performed by a communication device, the method comprising:
measuring a respective beam quality for each of a plurality of beams of a cell;
identifying M beams whose beam qualities are within a range which is determined based on a best beam quality among the respective beam quality for the each of the plurality of beams and a predetermined value; and
deriving a cell quality for the cell based on a linear average of beam qualities for the M beams, where M does not exceed a predetermined number of beams defined by a parameter.
2. The method according to claim 1 , further comprising reporting the cell quality to a base station in a measurement report.
3. The method according to claim 2 , further comprising determining a correlation between at least one pair of beams of a first and/or second group.
4. The method according to claim 3 , wherein information identifying the correlation is included in the measurement report separately from the cell quality.
5. The method according to claim 3 , wherein the cell quality is further derived based on the correlation.
6. The method according to claim 2 , wherein information identifying the M is included in the measurement report separately from the cell quality.
7. The method according to claim 2 , wherein the cell quality is further derived based on the M.
8. The method according to claim 1 , wherein the cell quality is derived based on the equation:
Cell Level Quality= f ( Q beam 1 ,Q beam 2 , . . . ,Q beam M ,M,C ) [Math.1]
where: Qbeami is a beam quality measured for a beam having an index, i; M is the number of beams used for deriving the cell quality; and C is a function of a correlation between beams in the cell.
9. The method according to claim 1 , wherein the cell quality is derived based on the equation:
[
Math
.
2
]
Cell
Level
Quality
=
Qbeam
1
+
∑
i
=
2
i
=
M
β
(
1
-
C
1
,
i
)
(
Qbeam
i
)
where Qbeam1 is a beam quality measured for the best beam in the cell, Qbeami is a beam quality measured for a beam having an index, i, β is a configurable value and Cj,i is a measure of a correlation between the beam having a beam index=j and a beam having a beam index=i.
10. The method according to claim 1 , wherein the cell quality is derived based on the equation:
Cell
Level
Quality
=
∑
i
=
1
i
=
M
W
i
×
QBeam
i
[
Math
.
3
]
where Qbeami is a beam quality measured for a beam having an index, i, and Wi is a weight applied to Qbeami.
11. The method according to claim 10 , wherein the weight (Wi) is derived based on the equation:
Wi=α i [Math.4]
where α is a configurable parameter that has a positive value that is less than 1 and i is a numerical beam index.
12. The method according to claim 1 , further comprising receiving information indicating at least one of the predetermined value and the predetermined number.
13. A communication device comprising:
a controller; and
a transceiver,
wherein the controller is configured to:
measure a respective beam quality for each of a plurality of beams of a cell;
identify M beams whose beam qualities are within a range which is determined based on a best beam quality among the respective beam quality for the each of the plurality of beams and a predetermined value; and
derive a cell quality for the cell based on a linear average of beam qualities for the M beams, where M does not exceed a predetermined number of beams defined by a parameter.
14. The communication device according to claim 13 , wherein the controller is configured to control the transceiver to receive information indicating at least one of the predetermined value and the predetermined number.