US 7,154,960 B2Granted

Method of determining the capacity of each transmitter antenna in a multiple input/multiple output (MIMO) wireless system

AssigneeLucent Technologies Inc.

InventorsJung-Tao Liu, Ashok N. Rudrapatna

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Abstract

The per antenna capacity of each of the transmitter antennas in a MIMO system are individually determined from measurable information at the receiver end. Specifically, the channel capacity for each individual transmitter antenna is calculated at the receiver end as a function of measurable channel coefficients (also known as channel state information), the measurable average signal-to-noise ratio, and the number of transmitter antennas. Once the per antenna capacity of each transmitter antenna is individually determined at the receiver end, the maximum transmission rate for each data stream transmitted by each transmitter antenna is determined from that individual capacity either at the receiver end and fed back to the transmitter end, or is determined at the transmitter end from the individual transmitter antenna capacities that are fed back by the receiver end to the transmitter end. A modulation scheme that supports each maximum transmission rate is then determined based on some defined criteria.

Claims14

Dependent claims

In a multiple input/multiple output wireless system in which a plurality of transmitter antennas at a transmitter end of the system transmit a plurality of signals on separate channels to a plurality of receiver antennas at a receiver end of the system, a method comprising:

determining, at the receiver end, instantaneous channel coefficients of each of the separate channels between the plurality of transmitter antennas and the plurality of receiver antennas;
determining an average signal-to-noise ratio of the signals received by the receiver antennas;
calculating, using the determined instantaneous channel coefficients and the determined average signal-to-noise ratio, the individual capacities of the transmitter antennas wherein the capacity of the k-th transmitter antenna, for k between 1 and t, is determined from the k-th term in
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where t is the number of transmitter antennas, ρ is the average signal-to-noise ratio of the received signals, I is an identity matrix, hj is an i-th column for any i between 1 and t of a channel matrix containing the determined channel coefficients in which each coefficient hij is the determined channel coefficient between the i-th transmitter antenna and the j-th receiver antenna, and hi+ is the Hermitian transpose of hi;
and
using the calculated individual capacities of the transmitter antennas, transmitting information back to the transmitter end so that when each transmitter antenna uses a determined data rate and modulation and coding scheme for each transmitter antenna, the calculated individual capacity of each transmitter antenna is not exceeded.

153 more elements

determining, at the receiver end, the individual capacity of each of the transmitter antennas from instantaneous channel coefficients of the separate channels and a measured average signal-to-noise ratio of the transmitted signals received at the receiver end wherein the capacity of the k-th transmitter antenna, for k between 1 and t, is determined from the k-th term in
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_
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+
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)
where t is the number of transmitter antennas, ρ is the average signal-to-noise ratio of the received signals, I is an identity matrix, hi is an i-th column for any i between 1 and t of a channel matrix containing the determined channel coefficients in which each coefficient hij is the determined channel coefficient between the i-th transmitter antenna and the j-th receiver antenna, and hi+ is the Hermitian transpose of hi;
and
using the determined individual capacity of each of the transmitter antennas, transmitting information back to the transmitter end so that when each transmitter antenna uses a determined data rate and modulation and coding scheme for each transmitter antenna, the calculated individual capacity of each transmitter antenna is not exceeded.

151 more elements

Apparatus at a receiver end of a multiple input/multiple output wireless system in which a plurality of transmitter antennas at a transmitter end of a wireless system transmit a plurality of signals on separate channels to a plurality of receiver antennas at the receiver end of the system, the apparatus comprising:

means for determining instantaneous channel coefficients of the each of the separate channels between the transmitter antennas and receiver antennas;
means for determining an average signal-to-noise ratio of the signals received by the receiver antenna;
means for calculating, using the determined instantaneous channel coefficients and the determined average signal-to-noise ratio, the individual capacities of each of the transmitter antennas wherein the capacity of the k-th transmitter antenna, for k between 1 and t, is determined from the k-th term in
log
2
⁡
(
1
+
ρ
t
⁢
h
_
1
+
(
I
+
ρ
t
⁢
∑
i
=
2
t
⁢
⁢
h
_
i
⁢
h
_
i
+
)
-
1
⁢
h
_
1
)
+
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2
⁡
(
1
+
ρ
t
⁢
h
_
2
+
(
I
+
ρ
t
⁢
∑
i
=
3
t
⁢
⁢
h
_
i
⁢
h
_
i
+
)
-
1
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h
_
2
)
+
log
2
⁡
(
1
+
ρ
t
⁢
h
_
3
+
⁡
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I
+
ρ
t
⁢
∑
i
=
4
t
⁢
⁢
h
_
i
⁢
h
_
i
+
)
-
1
⁢
h
_
3
)
+
⋯
+
log
2
⁡
(
1
+
ρ
t
⁢
h
_
t
+
⁢
h
_
t
)
where t is the number of transmitter antennas, ρ is the average signal-to-noise ratio of the received signals, I is an identity matrix, hi is an i-th column for any i between 1 and t of a channel matrix containing the determined channel coefficients in which each coefficient hij is the determined channel coefficient between the i-th transmitter antenna and the j-th receiver antenna, and hi+ is the Hermitian transpose of hi;
and
means for transmitting information back to the transmitter end that uses the individual capacities of each of the transmitter antennas calculated by the calculating means so that when each transmitter antenna uses a determined data rate and modulation and coding scheme for each transmitter antenna, the calculated individual capacity of each transmitter antenna is not exceeded.

153 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/334,314Filed 31 Dec 2002
Published: US 2004/0125900 A11 Jul 2004
Granted: 26 Dec 2006
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

H04L 1/0068
Rate matching: by puncturing
H04B 7/04
Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas: using two or more spaced independent antennas
H04L 1/0003
By adapting the transmission rate: by switching between different modulation schemes
H04L 1/0013
By adapting the channel coding: rate matching, e.g. puncturing or repetition of code symbols