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Table 1 Formulas applied to training or data frames for obtaining the different parameters

From: Experimental evaluation of interference alignment for broadband WLAN systems

Training frames (\(\mathring{z}_{s,n}=\mathring{z}_{s}\;\forall n\))
Channel Signal power
\(h_{s}=\frac {\sum _{n}z_{s,n}}{M\mathring{z}_{s}}\) \( S_{s}=\left |\frac {\sum _{n}z_{s,n}}{M}\right |^{2}\)
Residual noise power Residual noise variance
\(N_{s}=\frac {\sum _{n}\left |z_{s,n}-h_{s}\mathring{z}_{s}\right |^{2}}{M}\) \( {\sigma ^{2}_{s}}=\frac {N_{s}}{\left |h_{s}\right |^{2}}\)
Data frames (EVM)
\( \text {EVM}_{s}=\frac {\sum _{n}\left |\bar {z}_{s,n}-\mathring{z}_{s,n}\right |^{2}}{\sum _{n}\left |\mathring{z}_{s,n}\right |^{2}}\)
\(\begin {array}{ll} z_{s,n}\text {: received symbol}& \bar {z}_{s,n}\text {: equalized received symbol}\\[-2pt] \mathring{z}_{s,n} \text {: transmitted symbol} & s\text {: subcarrier index}\\[-2pt] \end {array}\)
n: OFDM symbol index (from 1 to N)
M: number of OFDM training symbols
N: number of OFDM data symbols