Method for receiving OFDM signal, and receiver
A receiver of an OFDM signal includes a reception unit to receive an OFDM signal formed by a plurality of OFDM symbols respectively including data subcarriers to which data signals are allocated and pilot subcarriers to which cyclically shifted pilot signals are allocated in frequency domain, an estimator to estimate phase errors of the pilot signals to generate first estimated values related to an offset of the OFDM symbol corresponding to each two or more OFDM symbols in the OFDM signal, a weighting adder to perform weighting additions on the first estimated values to obtain one second estimated value related to the offset, a compensator to compensate the offset by using the second estimated value to obtain a compensated OFDM signal, and a decoder to decode the compensated OFDM signal to reproduce the data signals.
1. A method for receiving an Orthogonal Frequency Division Multiplexed (OFDM) signal, comprising:
receiving an OFDM signal formed by a plurality of OFDM symbols respectively including data subcarriers to which data signals are allocated and pilot subcarriers to which pilot signals are allocated, where signal values of the pilot signals are cyclically shifted in frequency domain for each OFDM symbol;
estimating phase errors of the pilot signals to generate first estimated values related to a phase offset of an OFDM symbol corresponding to each two or more OFDM symbols in the OFDM signal;
performing weighting additions on the first estimated values to obtain one second estimate related to the offset;
compensating the offset by using the second estimated value to obtain a compensated OFDM signal; and
decoding the compensated OFDM signal to reproduce the data signals,
wherein
the OFDM signal is configured so that pilot signals P k,m and P l,m transmitted by m-th pilot subcarriers on frequency axes of a k-th and an l-th pilot subcarriers, respectively, satisfy the following equation:
∑
m
=
1
M
p
k
,
m
p
l
,
m
=
αδ
k
-
l
where M is a number of the pilot subcarriers, α is an arbitrary complex number, and δ is a delta function,
the pilot signals P k,m and P l,m are respectively configured each one OFDM symbol of the OFDM signal and with a period of N (N is integer two or more) OFDM symbols, and
estimating the phase errors generates N pieces of first distortion estimated values corresponding to each N OFDM symbols.
2. A method for receiving an Orthogonal Frequency Division Multiplexed (OFDM) signal, comprising:
receiving an OFDM signal formed by a plurality of OFDM symbols respectively including data subcarriers to which data signals are allocated and pilot subcarriers to which pilot signals are allocated, where signal values of the pilot signals are cyclically shifted in frequency domain for each OFDM symbol;
estimating phase errors of the pilot signals to generate first estimated values related to a phase offset of an OFDM symbol corresponding to each two or more OFDM symbols in the OFDM signal;
selecting one estimated value corresponding to a larger reception level of a receiver from the estimated values to obtain one second estimate related to the offset;
compensating the offset by using the second estimated value to obtain a compensated OFDM signal; and
decoding the compensated OFDM signal to reproduce the data signals,
wherein the OFDM signal is configured so that pilot signals P k,m and P l,m transmitted by m-th pilot subcarriers on frequency axes of a k-th and an l-th pilot subcarriers, respectively, satisfy the following equation:
∑
m
=
1
M
p
k
,
m
p
l
,
m
=
αδ
k
-
l
where M is a number of the pilot subcarriers, α is an arbitrary complex number, and δ is a delta function,
the pilot signals P k,m P l,m are respectively configured to be cyclically shifted for each one OFDM symbol of the OFDM signal and with a period of N (N is integer two or more) OFDM symbols, and
estimating the phase errors generates N pieces of first distortion estimated values corresponding to each N OFDM symbols.
3. A receiver of an Orthogonal Frequency Division Multiplexed (OFDM) signal, comprising:
a reception unit to receive an OFDM signal formed by a plurality of OFDM symbols respectively including data subcarriers to which data signals are allocated and pilot subcarriers to which pilot signals are allocated, where signal values of the pilot signals are cyclically shifted in frequency domain for each OFDM symbol;
an estimator to estimate phase errors of the pilot signals to generate first estimated values related to a phase offset of an OFDM symbol corresponding to each two or more OFDM symbols in the OFDM signal;
a weighting adder to perform weighting additions on the first estimated values to obtain one second estimated value related to the offset;
a compensator to compensate the offset by using the second estimated value to obtain a compensated OFDM signal; and
a decoder to decode the compensated OFDM signal to reproduce the data signals,
wherein the OFDM signal is configured so that pilot signals P k,m and P l,m transmitted by m-th pilot subcarriers on frequency axes of a k-th and an l-th pilot subcarriers, respectively, satisfy the following equation:
∑
m
=
1
M
p
k
,
m
p
l
,
m
=
αδ
k
-
1
where M is a number of the pilot subcarriers, α is an arbitrary complex number, and δ is a delta function,
the pilot signals P k,m and P l,m are respectively configured to be cyclically shifted for each one OFDM symbol of the OFDM signal and with a period of N (N is integer two or more) OFDM symbols, and
the estimator is configured to generate N pieces of first distortion estimated values corresponding to each N OFDM symbols.
4. The receiver according to claim 3 , wherein
the OFDM signal is configured so that a pilot signal of a k-th OFDM symbol is expressed by the following equation:
P k,m ( n )= P k ,( n+m )mod N
where N is a period of a cyclic shift of the pilot subcarrier, and
the estimator is configured to generate an estimated value of a clock offset that is one of the phase offsets corresponding to N OFDM symbols, or corresponding to integral multiples of N, as the first estimated value.
5. The receiver according to claim 3 , wherein
the second estimated value is generated for each data subcarriers and pilot subcarriers of the received OFDM signal, and
the compensator is configured to compensate a carrier offset that is a phase offset estimated by using the second estimated value.
6. The receiver according to claim 3 , wherein
the second estimated value is generated for each data subcarriers and pilot subcarriers, and
the compensator is configured to compensate a clock offset that is a phase offset estimated by using the second estimated value.
7. The receiver according to claim 3 , wherein
the second estimated value is generated for each data subcarriers and pilot subcarriers, and
the compensator is configured to compensate a clock offset that is a phase offset estimated by using the second estimated value, and further compensate a carrier offset that is another phase offset estimated by phase errors of the data subcarriers and the pilot subcarriers, for each one OFDM symbol.
8. A receiver of an orthogonal frequency division multiplexed (OFDM) signal, comprising:
a reception unit to receive an OFDM signal formed by a plurality of OFDM symbols respectively including data subcarriers to which data signals are allocated and pilot subcarriers to which pilot signals are allocated, where signal values of the pilot signals are cyclically shifted in frequency domain for each OFDM symbol;
an estimator to estimate phase errors of the pilot signals to generate first estimated values related to a phase offset of an OFDM symbol corresponding to each two or more OFDM symbols in the OFDM signal;
a selector to select one estimated value corresponding to a larger reception level of the receiver from the estimated values to obtain one second estimate related to the offset;
a compensator to compensate the offset by using the second estimated value to obtain a compensated OFDM signal; and
a decoder to decode the compensated OFDM signal to reproduce the data signals,
wherein the OFDM signal is configured so that pilot signals P k,m and P l,m transmitted by m-th pilot subcarriers on frequency axes of a k-th and an l-th pilot subcarriers, respectively, satisfy the following equation:
∑
m
=
1
M
p
k
,
m
p
l
,
m
=
αδ
k
-
1
where M is a number of the pilot subcarriers, α is an arbitrary complex number, and δ is a delta function,
the pilot signals P k,m and P l,m are respectively configured to be cyclically shifted for each one OFDM symbol of the OFDM signal and with a period of N (N is integer two or more) OFDM symbols, and
the estimator is configured to generate N pieces of first distortion estimated values corresponding to each N OFDM symbols.
9. The receiver according to claim 8 , wherein
the OFDM signal is configured so that a pilot signal of a k-th OFDM symbol is expressed by the following equation:
P k,m ( n )= P k ,( n+m )mod N
where N is a period of a cyclic shift of the pilot subcarrier, and
the estimator is configured to generate an estimated value of a clock offset that is one of the phase offsets corresponding to N OFDM symbols, or corresponding to integral multiples of N, as the first estimated value.
10. The receiver according to claim 8 , wherein
the second estimated value is generated for each data subcarriers and pilot subcarriers of the received OFDM signal, and
the compensator is configured to compensate a carrier offset that is a phase offset estimated by using the second estimated value.
11. The receiver according to claim 8 , wherein
the second estimated value is generated for each data subcarriers and pilot subcarriers, and
the compensator is configured to compensate a clock offset that is a phase offset estimated by using the second estimated value.
12. The receiver according to claim 8 , wherein
the second estimated value is generated for each data subcarriers and pilot subcarriers, and
the compensator is configured to compensate a clock offset that is a phase offset estimated by using the second estimated value, and further compensate a carrier offset that is another phase offset estimated by phase errors of the data subcarriers and the pilot subcarriers, for each one OFDM symbol.