the error vector magnitude (EVM), which is a common quality measure of transceivers.[^5] The 3GPP LTE standards specify EVM requirements in the range $[0.05,0.175]$, where higher-order modulations are supported if the EVM is below the lower part of this range [@Holma2011a]. Note that the ideal hardware case is obtained by simply setting $\epsilon = 0$.

Channel Acquisition
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As it is known, coherent processing of the received signal ${\mathbf{y}}_0$ requires knowledge of the UL channel vectors ${\mathbf{h}}_{00i}$ for $i=1,\ldots,K$. For this purpose, we assume that $B$ out of the $S$ symbols in each UL block are used for pilot transmission. This means that in the whole network there exists $B$ orthogonal pilot symbols that are shared among the cells. We assume that each BS picks $K \le B$ pilot symbols uniformly at random in each block, to avoid cumbersome pilot coordination. This means that on average $K/B$ of the cells reuse any given pilot symbol. We call $\beta = \frac{B}{K} \ge 1$ the pilot reuse factor such that $\beta K= B\le S$. In this setting, the pilot symbol, sent by the typical UE and received at the typical BS, is interfered with by the subset of cells in which there 