Channel estimation for wireless systems with multiple transmit 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 one or more communication channels is performed by selecting a plurality of training symbols disposed within said at least the set of first symbols and the set of second symbols, where a correlation between two different sets of said training symbols is zero;
wherein at least the first communication channel is based on a constant-modulus technique;
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 an 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
wherein characterizing the first communication channel further includes time-averaging at least one pre-estimate to produce a set of time-averaged estimates.
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. 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 one or more communication channels is performed by selecting a plurality of training symbols disposed within said at least the set of first symbols and the set of second symbols, where a correlation between two different sets of said training symbols is zero;
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;
wherein determining the set of first channel characteristics includes determining at least a set of first pre-estimates {overscore (h)} 1 [n]; and
wherein the set of first pre-estimates {overscore (h)} 1 [n] is determined based on an 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 set of previously determined channel characteristics.
4. 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 one or more communication channels is performed by selecting a plurality of training symbols disposed within said at least the set of first symbols and the set of second symbols, where a correlation between two different sets of said training symbols is zero;
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;
wherein determining the set of first channel characteristics includes determining at least a set of first pre-estimates {overscore (h)} 1 [n]; and
wherein characterizing the first communication channel further includes time-averaging at least one pre-estimate to produce a set of time-averaged estimates.
5. The method of claim 4 , 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.