Anti-aliasing channel estimation apparatus and method and receiver
An anti-aliasing channel estimation apparatus and method and a receiver where the anti-aliasing channel estimation method includes: performing clock recovery and data synchronization on a received multicarrier signal with channel aliasing, to obtain a synchronized time-domain signal and a sampling phase; calculating an estimation signal after passing through a channel and being aliased based on a training sequence and the sampling phase, and obtaining a channel response and an aliasing signal response of each subcarrier of the multicarrier signal based on the estimation signal and the frequency-domain signal. Therefore, channel estimation may be performed on the multicarrier signal with channel aliasing, influence of the channel aliasing on the bit error rate may be lowered, and transmission quality of the system may be improved.
1. An anti-aliasing channel estimation apparatus, comprising:
a processor configured to execute instructions to:
perform clock recovery and data synchronization on a received multicarrier signal with channel aliasing, to obtain a synchronized time-domain signal and a sampling phase;
transform the multicarrier signal from the time-domain signal into a frequency-domain signal by using a fast Fourier transform;
equalize the frequency-domain signal based on the sampling phase and an equalization coefficient; and
calculate an estimation signal after the multicarrier signal passing through a channel and being aliased based on a training sequence and the sampling phase, and obtain a channel response and an aliasing signal response of each subcarrier of the multicarrier signal based on the estimation signal and the frequency-domain signal.
2. The channel estimation apparatus according to claim 1 , wherein the processor is configured to execute the instructions to:
transform sampling phase ϕ into e jϕ and e −jϕ ;
calculate estimation signal tx(e jϕ +e −jϕ ) after passing through a channel and being aliased based on a transformed sampling phase and training sequence tx; and
calculate the channel response and the aliasing signal response of each subcarrier of the multicarrier signal based on frequency-domain signal rx and the estimation signal tx(e jϕ +e −jϕ ).
3. The channel estimation apparatus according to claim 2 , wherein the processor is configured to execute the instructions to:
obtain the equalization coefficient according to the channel response;
obtain channel noise according to the frequency-domain signal, the equalization coefficient and the training sequence; and
calculate a signal to noise ratio based on the channel noise and the training sequence.
4. The channel estimation apparatus according to claim 3 , wherein the processor is configured to execute the instructions to obtain the channel noise by multiplying the frequency-domain signal by the equalization coefficient and subtract the training sequence.
5. The channel estimation apparatus according to claim 2 , wherein the processor is configured to execute the instructions to perform calculation by using a formula below:
[
tx
1
e
j
ϕ
1
tx
1
e
-
j
ϕ
1
tx
2
e
j
ϕ
2
tx
2
e
-
j
ϕ
2
⋮
]
×
[
h
1
h
2
]
=
[
rx
1
rx
2
⋮
]
;
where, tx n is the training sequence, rx n is the frequency-domain signal, ϕ n is the sampling phase, h 1 is the channel response, and h 2 is the aliasing signal response.
6. The channel estimation apparatus according to claim 5 , wherein the processor is configured to execute the instructions to obtain the channel response h 1 and the aliasing signal response h 2 using one of a matrix division method and a minimum mean square error algorithm.
7. An anti-aliasing channel estimation method, comprising:
performing clock recovery and data synchronization on a received multicarrier signal with channel aliasing, to obtain a synchronized time-domain signal and a sampling phase;
transforming the multicarrier signal from the time-domain signal into a frequency-domain signal by using fast Fourier transform;
equalizing the frequency-domain signal based on the sampling phase and an equalization coefficient; and
calculating an estimation signal after the multicarrier signal passing through a channel and being aliased based on a training sequence and the sampling phase, and obtaining a channel response and an aliasing signal response of each subcarrier of the multicarrier signal based on the estimation signal and the frequency-domain signal.
8. The channel estimation method according to claim 7 , wherein the calculating an estimation signal passing through a channel and being aliased based on a training sequence and the sampling phase, and obtaining a channel response and an aliasing signal response of each subcarrier of the multicarrier signal based on the estimation signal and the frequency-domain signal, comprises:
transforming sampling phase ϕ into e jϕ and e −jϕ ;
calculating estimation signal tx(e jϕ +e −jϕ ) after passing through a channel and being aliased based on a transformed sampling phase and training sequence tx;
calculating the channel response and the aliasing signal response of each subcarrier of the multicarrier signal based on frequency-domain signal rx and the estimation signal tx(e jϕ +e −jϕ ).
9. The channel estimation method according to claim 8 , wherein the channel estimation method further comprises:
obtaining the equalization coefficient according to the channel response;
obtaining channel noise according to the frequency-domain signal, the equalization coefficient and the training sequence; and
calculating a signal to noise ratio based on the channel noise and the training sequence.
10. A receiver of a multicarrier system, which is configured to receive a multicarrier signal with channel aliasing, characterized in that the receiver comprises the anti-aliasing channel estimation apparatus according to claim 1 .