  Hybrid beamforming has evolved as a promising technology that offers the
balance between system performance and design complexity in mmWave MIMO
systems. Existing hybrid beamforming methods either impose unit-modulus
constraints or a codebook constraint on the analog precoders/combiners, which
in turn results in a performance-overhead tradeoff. This paper puts forth a
tensor framework to handle the wideband hybrid beamforming problem, with
Vandermonde constraints on the analog precoders/combiners. The proposed method
strikes the balance between performance, overhead and complexity. Numerical
results on a 3GPP link-level test bench reveal the efficacy of the proposed
approach relative to the codebook-based method while attaining the same
feedback overhead. Moreover, the proposed method is shown to achieve comparable
performance to the unit-modulus approaches, with substantial reductions in
overhead.
