Coordinated multi-point transmission
View Patent ↗In a multiple-input multiple-output (MIMO) wireless system supporting Coordinated Multi-Point (CoMP) transmission and having a first base station, a second base station, and a user equipment, a communications method implemented in the first base station is disclosed. In an aspect, the communications method includes exchanging, with the second base station through local information exchange, first information about a first channel between the first base station and the user equipment and second information about a second channel between the second base station and the user equipment, and computing at least one of a precoding matrix, a receiver filter, and a projection matrix, wherein the user equipment estimates the first information and the second information, and shares the first information and the second information with the first base station. Other apparatuses and some methods for wireless communications also are disclosed.
1. In a multiple-input multiple-output (MIMO) wireless system supporting Coordinated Multi-Point (COMP) transmission and having a first base station, a second base station, and a user equipment, a communications method implemented in the first base station, the communications method comprising:
exchanging, with the second base station through local information exchange, first information about a first channel between the first base station and the user equipment and second information about a second channel between the second base station and the user equipment; and
computing at least one of a precoding matrix, a receiver filter, and a projection matrix U and V and user k, streams of data d, potential interference P, link i and neighboring link j, and + is a complex conjugate operator, comprising determining:
U
[
i
]
=
arg
min
U
[
k
]
I
[
t
]
=
Tr
[
(
U
[
k
]
)
†
Q
[
i
]
U
[
k
]
]
where
Q
[
i
]
=
∑
j
∈
R
(
i
)
P
d
H
[
ij
]
V
[
j
]
(
V
[
j
]
)
†
(
H
[
ij
]
)
†
,
and
wherein the method further comprises the steps of estimating, by the user equipment, the first information and the second information, and sharing the first information and the second information with the first base station.
2. The communications method as in claim 1 , further comprising:
attempting to decode an uplink signal from the user equipment;
sharing the decoded signal with the second base station, if the attempt is successful; and
sending a message to a coordinator, if the attempt is unsuccessful.
3. The communications method as in claim 2 ,
wherein information about the precoding matrix is shared or before the decoded signal is shared the decoded signal is precoded.
4. The communications method as in claim 1 , further comprising:
calculating a first post-scheduling Signal to Interference plus Noise Ratio (SINR) for the user equipment; and
scheduling the user equipment for transmission, if the first post-scheduling SINR exceeds a first threshold.
5. The communications method as in claim 4 ,
wherein the first threshold is different from a decodability threshold.
6. The communications method as in claim 5 , wherein the decodability threshold comprises ability or possibility to decode the message.
7. The communications method as in claim 4 , further comprising:
providing information about an interfering signal to the second base station.
8. The communications method as in claim 7 ,
wherein raw data of the user equipment is shared by the first base station and the second base station.
9. The communications method as in claim 7 ,
wherein the information comprises a signal to be transmitted from the first base station.
10. The communications method as in claim 7 ,
wherein the provided information comprises a signal dirty-paper-coded to cancel interference before transmission.
11. The communications method as in claim 7 , wherein the information comprises a signal Tomlinson-Harashima-precoded to cancel interference before transmission.
12. The communications method as in claim 4 , further comprising:
recalculating, according to information about a decodable user equipment, a second post-scheduling SINR for the user equipment if the first post-scheduling SINR does not exceed a second threshold.
13. The communications method as in claim 12 , wherein the second threshold is the same as the first threshold.
14. The communications method as in claim 12 , further comprising:
iterating the recalculation until a predetermined number of iteration is reached or no more user equipment becomes decodable.
15. The communications method as in claim 14 ,
wherein the first base station and the second base station substantially simultaneously transmits a downlink signal upon reception of a sync signal from a coordinator.
16. In a multiple-input multiple-output (MIMO) wireless system supporting Coordinated Multi-Point (CoMP) transmission and having a first base station, a second base station, a first user equipment, and a second user equipment, a communications method implemented in the first user equipment, the communications method comprising:
exchanging, with the second user equipment through local information exchange, first information about a first channel between the first base station and the first user equipment and second information about a second channel between the second base station and the first user equipment; and
computing at least one of a precoding matrix, a receiver filter, and a projection matrix U and V and user k, streams of data d, potential interference P, link i and neighboring link j, and + is a complex conjugate operator, comprising determining:
U
[
i
]
=
arg
min
U
[
k
]
I
[
t
]
=
Tr
[
(
U
[
k
]
)
†
Q
[
i
]
U
[
k
]
]
where
Q
[
i
]
=
∑
j
∈
R
(
i
)
P
d
H
[
ij
]
V
[
j
]
(
V
[
j
]
)
†
(
H
[
ij
]
)
†
,
and
wherein the method further comprises the steps of estimating, by the first user equipment estimates the first information and the second information, and sharing the first information and the second information with the first base station and the second base station.
17. The communications method as in claim 16 ,
wherein the first base station attempts to decode an uplink signal from the first user equipment,
wherein the first base station shares the decoded signal with the second base station, if the attempt is successful, and
wherein the first base station sends a message to a coordinator, if the attempt is unsuccessful.
18. The communications method as in claim 16 , wherein the first base station calculates a first post-scheduling Signal to Interference plus Noise Ratio (SINR) for the user equipment, and
wherein the first base station schedules the user equipment for transmission, if the first post-scheduling SINR exceeds a first threshold.
19. A multiple-input multiple-output (MIMO) wireless system supporting Coordinated Multi-Point (CoMP) transmission, the MIMO wireless system comprising:
a first base station;
a second base station; and
a user equipment,
wherein the first base station is configured to exchange, with the second base station through local information exchange, first information about a first channel between the first base station and the user equipment and second information about a second channel between the second base station and the user equipment,
wherein the first base station is configured to compute at least one of a precoding matrix, a receiver filter, and a projection matrix U and V and user k, streams of data d, potential interference P, link i and neighboring link j, and + is a complex conjugate operator, comprising determining:
U
[
i
]
=
arg
min
U
[
k
]
I
[
t
]
=
Tr
[
(
U
[
k
]
)
†
Q
[
i
]
U
[
k
]
]
where
Q
[
i
]
=
∑
j
∈
R
(
i
)
P
d
H
[
ij
]
V
[
j
]
(
V
[
j
]
)
†
(
H
[
ij
]
)
†
,
and
wherein the user equipment is configured to estimate the first information and the second information, and to share the first information and the second information with the first base station.
20. A multiple-input multiple-output (MIMO) wireless system supporting Coordinated Multi-Point (CoMP) transmission, the MIMO wireless system comprising:
a first base station;
a second base station;
a first user equipment; and
a second user equipment,
wherein the first user equipment exchanges, with the second user equipment through local information exchange, first information about a first channel between the first base station and the first user equipment and second information about a second channel between the second base station and the first user equipment,
wherein the first user equipment computes at least one of a precoding matrix, a receiver filter, and a projection matrix U and V and user k, streams of data d, potential interference P, link i and neighboring link j, and + is a complex conjugate operator, comprising determining:
U
[
i
]
=
arg
min
U
[
k
]
I
[
t
]
=
Tr
[
(
U
[
k
]
)
†
Q
[
i
]
U
[
k
]
]
where
Q
[
i
]
=
∑
j
∈
R
(
i
)
P
d
H
[
ij
]
V
[
j
]
(
V
[
j
]
)
†
(
H
[
ij
]
)
†
,
and
wherein the first user equipment is configured to estimate the first information and the second information, and to share the first information and the second information with the first base station and the second base station.