Method and system for wireless communication channel estimation
A method and system for selecting an algorithm for channel estimation in a wireless communication system are disclosed. According a parameter indicative of an accuracy of a channel estimation algorithm is determined. A selection between a first channel estimation algorithm and a second channel estimation algorithm is made based on the determined parameter.
1. A method of selecting an algorithm for channel estimation in a communication system, the method comprising:
calculating a parameter indicative of an accuracy of a channel estimation algorithm, the parameter being calculated based on a summation of square differences of channel estimates at different times normalized by an estimated received power, the estimate of the received power being determined after channel estimation, the summation being over a number of transmit antennas, a number of receive antennas, and a number of subcarriers; and
selecting between a first channel estimation algorithm and a second channel estimation algorithm based on the parameter.
2. The method of claim 1 , wherein the parameter indicative of the accuracy of the channel estimation algorithm is a parameter indicative of an amount of a temporal variation in a channel estimate.
3. The method of claim 2 , wherein the selecting includes:
comparing the parameter to a threshold; and
determining when the parameter indicates one of a low temporal variation and a high temporal variation.
4. The method of claim 3 , wherein an averaging algorithm is selected if the parameter indicates a low temporal variation, and a linear interpolation algorithm is selected if the parameter indicates a high temporal variation.
5. The method of claim 3 , wherein the threshold is based at least in part on a probability distribution of the parameter.
6. The method of claim 1 , wherein the parameter is based on an error function.
7. The method of claim 6 , wherein the parameter is based on a difference between an approximate mean square error of an averaging algorithm and an approximate mean square error of a linear interpolation algorithm.
8. A method of selecting an algorithm for channel estimation in a communication system, the method comprising:
calculating a parameter indicative of an amount of a temporal variation in a channel estimate, the parameter being calculated based on a summation of square differences of channel estimates at different times;
selecting between a first channel estimation algorithm and a second channel estimation algorithm based on the parameter; and
the selecting including:
comparing the parameter to a threshold, the threshold being based at least in part on a probability distribution of the parameter, the threshold being further based at least in part on a signal to noise ratio of a signal transmitted through the channel, the signal to noise ratio being measured after channel estimation; and
determining when the parameter indicates one of a low temporal variation and a high temporal variation.
9. A method of selecting an algorithm for channel estimation in a communication system, the method comprising:
calculating a parameter indicative of an accuracy of a channel estimation algorithm, the parameter being calculated based on a summation of square differences of channel estimates at different times, the parameter being indicative of an amount of a temporal variation in a channel estimate; and
selecting between a first channel estimation algorithm and a second channel estimation algorithm based on the parameter, the selecting including:
comparing the parameter to a threshold, the threshold being approximated by a polynomial function based on a probability distribution of the parameter; and
determining when the parameter indicates one of a low temporal variation and a high temporal variation, the threshold being approximated by
Θ
(
p
)
=
Θ
~
(
p
)
S
N
~
R
lin
where SÑR lin is an estimated received signal to noise ratio in linear scale after channel estimation, and
{tilde over (Θ)}( p )≈−2.3339 p 4 +8.0448 p 3 −10.8173 p 2 +6.8343 p− 0.7244
where pε[50,100]% is a percentage point.
10. A method of selecting an algorithm for channel estimation in a communication system, the method comprising:
calculating a parameter indicative of an accuracy of a channel estimation algorithm, the parameter being calculated based on a summation of square differences of channel estimates at different times normalized by an estimated received power, the estimate of the received power being determined after channel estimation;
selecting between a first channel estimation algorithm and a second channel estimation algorithm based on the parameter, the parameter being given by:
θ
n
=
θ
P
~
r
and where {tilde over (P)} r is an estimated received power after channel estimation and the summation is given by one of
θ
=
1
2
N
T
N
R
F
∑
j
=
1
N
T
∑
i
=
1
N
R
∑
f
=
1
F
(
Re
(
H
~
f
ij
(
n
1
)
)
-
Re
(
H
~
f
ij
(
n
2
)
)
)
2
+
(
Im
(
H
~
f
ij
(
n
1
)
)
-
Im
(
H
~
f
ij
(
n
2
)
)
)
2
and a multiple thereof, and where N T is a quantity of transmit antennas, N R is a quantity of receive antennas, F is a number of subcarriers, and {tilde over (H)} f ij (n k ) is an estimate of the channel frequency response between antennas i and j at a time n k of the f th subcarrier.
11. A method of selecting an algorithm for channel estimation in a communication system, the method comprising:
calculating a parameter indicative of an accuracy of a channel estimation algorithm, the parameter being calculated based on a summation of square differences of channel estimates at different times, the parameter being further based on a difference between an approximate mean square error of an averaging algorithm and an approximate mean square error of a linear interpolation algorithm, the difference being approximately given by
MSE Δ =MSE avg −MSE linear ≈8 P (1 −J 0 (7ω 0 ))−8.28σ z 2
where P is a transmit signal power, J o is a zero order Bessel function of the first kind, ω o is ω 0 =2πf D T s f D a Doppler frequency, T s is the OFDM symbol interval and σ z 2 is an estimation of a noise variance of a channel, and where J 0 (7ω 0 ) is obtained from θ=2P(1−J 0 (7ω 0 ))+2σ z 2 ; and
selecting between a first channel estimation algorithm and a second channel estimation algorithm based on the parameter.
12. A non-transitory computer readable medium containing computer readable instruction that, when executed by a processor, cause the processor to perform functions that include:
calculating a parameter indicative of an accuracy of a channel estimation algorithm for estimating a channel in a communication system, the parameter being calculated based on a summation of square differences of channel estimates at different times, the parameter being based at least in part on a temporal variation of the channel, the parameter being further based at least in part on a measure of an estimated received signal to noise ratio after channel estimation; and
selecting a channel estimation algorithm to estimate a channel based on the parameter.
13. The non-transitory computer readable medium of claim 12 , wherein the parameter is based on a first error associated with a first algorithm and a second error associated with a second algorithm.
14. The non-transitory computer readable medium of claim 13 , wherein the first error and the second error are mean square errors, the first algorithm being an averaging algorithm and the second algorithm being a linear interpolation algorithm.