Channel estimation for wireless systems with multiple transit antennas
View Patent ↗In various embodiments, techniques are provided to determine channel characteristics of various communication systems such as OFDM systems or systems using a plurality of transmit antennas by using various sets of training symbols.
1. A method of characterizing one or more communication channels, comprising:
receiving a set of first symbols associated with a first communication channel;
receiving a set of second symbols associated with a second communication channel;
characterizing at least a first communication channel based on at least the set of first symbols and the set of second symbols to produce a set of first channel characteristics, wherein characterizing the first communication channel includes:
performing a first correlation to produce a set of first correlations; and
determining the set of first channel characteristics based on at least the set of first correlations, wherein determining the set of first channel characteristics includes determining at least a set of first pre-estimates {overscore (h)} 1 [n], wherein the set of first pre-estimates {overscore (h)} 1 [n]is determined based on the equation:
h
_
i
[
n
]
=
1
K
p
i
[
n
]
,
wherein p i [n]is the set of first correlations and K is a constant; and time-averaging at least one pre-estimate to produce a set of time-averaged estimates;
wherein characterizing one or more communication channels is performed without a matrix inversion;
wherein at least the first communication channel is based on a constant-modulus technique.
2. The method of claim 1 , wherein characterizing the first communication channel further includes performing a transform on the set of time-averaged estimates to produce a set of channel characteristics.
3. The method of claim 2 , wherein characterizing two or more communication channels does not use a matrix inversion.
4. The method of claim 2 , wherein a first set of training signals is transmitted using a first transmit device and one or more sets of second training signals is transmitted using a second transmitting device.
5. A method of characterizing one or more communication channels, comprising:
receiving a set of first symbols associated with a first communication channel;
receiving a set of second symbols associated with a second communication channel;
characterizing at least a first communication channel based on at least the set of first symbols and the set of second symbols to produce a set of first channel characteristics, wherein characterizing the first communication channel includes:
performing a first correlation to produce a set of first correlations;
performing a second correlation to produce a set of second correlations; and
determining a set of channel pre-estimates based on at least the first correlation product and the second correlation product, by determining at least a set of first pre-estimates {overscore (h)} 1 [n], wherein the set of first pre-estimates {overscore (h)} 1 [n] is determined based on the equation:
h
_
i
[
n
]
=
1
K
(
p
i
[
n
]
-
∑
g
=
1
i
≠
g
Q
gi
[
n
]
h
~
g
[
n
-
1
]
)
,
wherein p i [n] is related to the set of first correlations, Q gi [n] is related to the set of second correlations, and K is a constant and {tilde over (h)} g [n−1] is related to a set of previously determined channel characteristics;
wherein characterizing one or more communication channels is performed without a matrix inversion.
6. A method of characterizing one or more communication channels, comprising:
receiving a set of first symbols associated with a first communication channel;
receiving a set of second symbols associated with a second communication channel;
characterizing at least a first communication channel based on at least the set of first symbols and the set of second symbols to produce a set of first channel characteristics, wherein characterizing the first communication channel includes:
performing a first correlation to produce a set of first correlations;
performing a second correlation to produce a set of second correlations;
determining a set of channel pre-estimates based on at least the first correlation product and the second correlation product, by determining at least a set of first pre-estimates {overscore (h)} 1 [n]; and
time-averaging at least one pre-estimate to produce a set of time-averaged estimates;
wherein characterizing one or more communication channels is performed without a matrix inversion.
7. The method of claim 6 , wherein characterizing the first communication channel further includes performing a transform on the set of time-averaged estimates to produce a set of channel characteristics.