A low-complexity sequential encoder for threshold vector perturbation

We propose a sequential encoder for threshold vector perturbation (TVP) precoding in the downlink of K-user multiple input single output (MISO) systems, that introduces complexity savings in the encoding of the data symbols at the base station (BS) transmitter. As opposed to conventional TVP where a thresholded K-dimensional search is carried out to obtain the perturbation vectors that satisfy given signal to noise ratio (SNR) thresholds at the receiver, here we explore a sequential approach that involves the encoding of a subset of transmit symbols L <K to obtain the required vectors. This limits the dimensionality of the associated sphere search, while still obtaining SNR-guaranteeing perturbation vectors. The presented analysis and results show significant complexity savings with the proposed scheme compared to conventional TVP and VP schemes.