  The transformative enhancements of fifth-generation (5G) mobile devices bring
about new challenges to achieve better uplink (UL) performance. Particularly,
in codebook-based transmission, the wide-band (WB) precoding and the legacy UL
codebook may become main bottlenecks for higher efficient data transmission. In
this paper, we investigate the codebook-based UL single-layer transmission
performance using fully coherent antenna ports in the context of sub-band (SB)
precoding. We analyze the SB precoder selection criteria and design an UL
codebook used for SB precoding by increasing the number of relative phase
shifts of each port. Via link-level simulations, we verify that the UL SB
precoding can improve up to 2 dB performance gain in terms of the block error
rate (BLER) compared with the UL WB precoding which is the current UL precoding
scheme. We also show that UL performance gain is sensitive to the SB size
selection as well as the relative phase shift diversity.
