Anti-sampling offset processing method and method for channel estimation in wireless communication system
View Patent ↗Provided are an anti-sampling offset processing method and apparatus for channel estimation in a wireless communication system, and the method includes: a main path threshold and a first side lobe threshold are acquired based on a result of IFFT during the channel estimation, wherein the first side lobe threshold is smaller than the main path threshold; a noise reduction threshold and a second side lobe threshold are acquired based on a measurement result of Interference on Signal Code Power (ISCP), wherein the second side lobe threshold is smaller than the noise reduction threshold; a predetermined number of strongest paths are selected from main paths determined according to the main path threshold and the noise reduction threshold and a predetermined number of paths adjacent to the strongest paths are labelled as side lobes; and the paths labelled as side lobes are selected according to a final threshold and paths equal to or larger than the final threshold are reserved for participation of subsequent demodulation, wherein the final threshold is the greater one of the first side lobe threshold and the second side lobe threshold. In the present disclosure, impacts of sampling offsets in a wireless communication system on channel estimation are taken into consideration, and side lobes of a main path are introduced into a demodulation process, thereby improving reception performance of a terminal in the wireless communication system.
1. An anti-sampling offset processing method for channel estimation in a wireless communication system, the method comprising:
a main path threshold determination step of acquiring a main path threshold and a first side lobe threshold based on a result of Inverse Fast Fourier Transform (IFFT) during the channel estimation, wherein the first side lobe threshold is smaller than the main path threshold;
a noise reduction threshold determination step of acquiring a noise reduction threshold and a second side lobe threshold based on a measurement result of Interference on Signal Code Power (ISCP), wherein the second side lobe threshold is smaller than the noise reduction threshold;
a side lobe determination processing step of selecting a predetermined number of strongest paths from main paths determined according to the main path threshold and the noise reduction threshold and labeling a predetermined number of paths adjacent to the strongest paths as side lobes; and
a side lobe selection processing step of selecting the paths labeled as side lobes according to a final threshold and reserving paths equal to or larger than the final threshold for participation of subsequent demodulation, wherein the final threshold is a greater one of the first side lobe threshold and the second side lobe threshold;
wherein in the main path threshold determination step, the main path threshold and the first side lobe threshold are determined based on a following formula:
Γ
j
(
i
)
=
λ
j
+
1
(
i
)
max
(
[
h
^
E
1
(
i
)
2
h
^
E
2
(
i
)
2
…
h
^
E
j
(
i
)
2
]
)
wherein ĥ Ej (i) , is a result of IFFT during an ith level channel estimation of a jth cell, λ j (i) is a threshold factor, wherein λ 1 (i) ˜λ j (i) is a main path threshold factor and a corresponding Γ (i) is the main path threshold, and λ j+1 (i) is a first side lobe threshold factor and a corresponding Γ (i) is the first side lobe threshold;
wherein a value of the first side lobe threshold factor is smaller than a value of the main path threshold factor.
2. The method according to claim 1 , wherein in the noise reduction threshold determination step, the noise reduction threshold and the second side lobe threshold are determined based on a following formula:
Ω j (i) =γ j+1 (i) δ 2(i)
wherein δ 2(i) is a noise measurement result of the ISCP during an ith level channel estimation, γ j (i) is a threshold factor, wherein λ 1 (i) ˜λ j (i) is a noise reduction threshold factor and a corresponding Ω (i) is the noise reduction threshold, and γ j+1 (i) is a second side lobe threshold factor and a corresponding Ω (i) is the second side lobe threshold;
wherein a value of the second side lobe threshold factor is smaller than a value of the noise reduction threshold factor.
3. The method according to claim 1 , wherein in the side lobe determination processing step, the predetermined number of paths comprise a same number of paths equally located on the left and the right of the strongest paths, and the same number is any one of 0 to 5 chips.
4. The method according to claim 1 , wherein in the side lobe determination processing step, the predetermined number of the strongest paths is any integer of 0 to 3, and the strongest paths are not labeled as side lobes.
5. The method according to claim 1 , wherein the side lobe determination processing step is performed only in a (n−1)th level of iteration in the channel estimation and the side lobe selection processing step is performed only in an nth level of iteration in the channel estimation, wherein n is a total number of levels of iteration.
6. An anti-sampling offset processing apparatus for channel estimation in a wireless communication system, the apparatus comprising:
a main path threshold determination module configured to acquire a main path threshold and a first side lobe threshold based on a result of Inverse Fast Fourier Transform (IFFT) during the channel estimation, wherein the first side lobe threshold is smaller than the main path threshold;
a noise reduction threshold determination module configured to acquire a noise reduction threshold and a second side lobe threshold based on a measurement result of Interference on Signal Code Power (ISCP), wherein the second side lobe threshold is smaller than the noise reduction threshold;
a side lobe determination processing module configured to select a predetermined number of strongest paths from main paths determined according to the main path threshold and the noise reduction threshold and to label a predetermined number of paths adjacent to the strongest paths as side lobes; and
a side lobe selection processing module configured to select the paths labelled as side lobes according to a final threshold and to reserve paths equal to or larger than the final threshold for participation of subsequent demodulation, wherein the final threshold is a greater one of the first side lobe threshold and the second side lobe threshold;
wherein the main path threshold determination module, the noise reduction threshold determination module, the side lobe determination processing module and the side lobe selection processing module are implemented by a Central Processing Unit (CPU), a Digital Signal Processor (DSP) or a Field Programmable Gate Array (FPGA);
wherein the main path threshold determination module determines the main path threshold and the first side lobe threshold based on a following formula:
Γ
j
(
i
)
=
λ
j
+
1
(
i
)
max
(
[
h
^
E
1
(
i
)
2
h
^
E
2
(
i
)
2
…
h
^
E
j
(
i
)
2
]
)
wherein ĥ Ej (i) is a result of IFFT during an ith level channel estimation of a jth cell, λ j (i) is a threshold factor, wherein λ 1 (i) ˜λ j (i) is a main path threshold factor and a corresponding Γ (i) is the main path threshold, and λ j+1 (i) is a first side lobe threshold factor and a corresponding Γ (i) is the first side lobe threshold;
wherein a value of the first side lobe threshold factor is smaller than a value of the main path threshold factor.
7. The anti-sampling offset processing apparatus according to claim 6 , wherein the noise reduction threshold determination module determines the noise reduction threshold and the second side lobe threshold based on a following formula:
Ω j (i) =γ j+1 (i) δ 2(i)
wherein δ 2(i) is a noise measurement result of the ISCP during an ith level channel estimation, γ j (i) is a threshold factor, wherein λ 1 (i) ˜λ j (i) is a noise reduction threshold factor and a corresponding Ω(i) is the noise reduction threshold, and γ j+1 (i) is a second side lobe threshold factor and a corresponding Ω (i) is the second side lobe threshold;
wherein a value of the second side lobe threshold factor is smaller than a value of the noise reduction threshold factor.
8. The anti-sampling offset processing apparatus according to claim 6 , wherein the predetermined number of paths comprise a same number of paths equally located on the left and the right of the strongest paths, and the same number is any one of 0 to 5 chips.
9. The anti-sampling offset processing apparatus according to claim 6 , wherein the predetermined number of the strongest paths is any integer of 0 to 3, and the strongest paths are not labeled as side lobes.
10. The anti-sampling offset processing apparatus according to claim 6 , wherein the side lobe determination processing module functions only in a (n−1)th level of iteration in the channel estimation and the side lobe selection processing module functions only in an nth level of iteration in the channel estimation, wherein n is a total number of levels of iteration.