  The uplink where both the transmitter and receiver can use a large antenna
array is considered. This is proposed as a method of antenna offloading and
connecting small cell access points (SCAP) in a Two-Tier cellular network. Due
to having a limited number of RF-chains, hybrid beamformers are designed where
phase-only processing is done at the RF-band, followed by digital processing at
the baseband. The proposed receiver is a row combiner that clusters
sufficiently correlated antenna elements, and its' performance is compared
against random projection via a Discrete Fourier Transform (DFT) matrix. The
analogue to the row combiner is a column spreader, which is dependent on the
transmit correlation, and repeats the transmitted signal over antenna elements
that are correlated. A key benefit of this approach is to reduce the number of
phase shifters used, while outperforming the DFT scheme. When only the
transmitter has correlation and is RF-chain limited, the baseband precoding
vectors are shown to be the eigenvectors of the effective transmit correlation
matrix. Depending on the channel correlation, this matrix can be approximated
to have a tridiagonal Toeplitz structure with the proposed column spreader
(CS). The resulting eigenvalues have a closed form solution which allows us to
characterize the sum rate of the system. Most interestingly, the associated
eigenvectors do not require knowledge of the effective transmit correlation
matrix to be calculated using an Eigenvalue Decomposition (EVD) method.
