Method for reducing interference in OFDM wireless networks
View Patent ↗Interference in a received orthogonal frequency division multiplexing (OFDM) symbol, modulated according to selected constellation points s k , is reduced. The symbol includes a set of pilot signals and a set of data signals y k , where k is a number of consecutive subcarriers used for the pilot and the data signals. The pilot signals are thresholded to detect interfering pilot signals, which are then erased. Channels Ĥ k are estimated using remaining pilot signals. The set of data signals are decoded based on the estimated channels Ĥ k , and, for each bit b i in the set of data signals, a logarithmic likely ratio (LLR) log ∑ s k : b i = 0 1 y k - H ^ k s k 2 ∑ s k : b i = 1 1 y k - H ^ k s k 2 is determined. The LLR is an indicator of the likely interference.
1. A method for reducing interference in a received orthogonal frequency division multiplexing (OFDM) symbol modulated according to selected constellation points s k , wherein the received symbol includes a set of pilot signals and a set of data signals y k , and k is a number of consecutive subcarriers used for the pilot and the data signals, comprising steps of:
thresholding the set of pilot signals to detect interfering pilot signals;
erasing the detected interfering pilot signals;
estimating channels Ĥ k using remaining pilot signals;
Ĥ k
determining, for each bit b i , in the set of data signals, a logarithmic likely ratio (LLR)
log
∑
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k
:
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;
and
decoding the set of data signals based on the determined LLR,
wherein the steps are performed in a receiver, wherein k and i are integers.
2. The method of claim 1 , wherein the interference in the received OFDM symbol is partial-band and partial-time interference.
3. The method of claim 1 , where the set of pilot signals is a combination of fixed and random pilot signals.
4. The method of claim 1 , wherein the thresholding step further comprises:
comparing a relative power of each pilot signal of the set of pilot signals to a variance of additive white Gaussian noise.
5. The method of claim 1 , further comprising:
feeding back each bits b i in the set of data signals to improve the estimating.
6. A method for reducing interference in an approximate received orthogonal frequency division multiplexing (OFDM) symbol modulated according to selected constellation points s k , wherein the received symbol includes a set of pilot signals and a set of approximate y k data signals, and k is a number of consecutive subcarriers used for the pilot and data signals, comprising steps of:
thresholding the set of pilot signals to detect interfering pilot signals;
erasing the detected interfering pilot signals;
estimating channels Ĥ k using remaining pilot signals;
Ĥ k
determining, for each bit b i , in the set of data signals, a logarithmic likely ratio (LLR)
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decoding the set of data signals based on the determined LLR,
wherein the steps are performed in a receiver, wherein k and i are integers, σ 2 is a variance of additive noise and {tilde over (Y)} k is an equalization of the received symbol.