  In this paper, we propose the use of a deterministic sequence, known as
unique word (UW), instead of the cyclic prefix (CP) in generalized frequency
division multiplexing (GFDM) systems. The UW consists of known sequences that,
if not null, can be used advantageously for synchronization and channel
estimation purposes. In addition, UW allows the application of a highly
efficient linear minimum mean squared error (LMMSE) smoother for noise
reduction at the receiver. To avoid the conditions of non-orthogonality caused
by the insertion of the UW and performance degradation in time varying
frequency-selective channels, we use frequency-shift offset quadrature
amplitude modulation (FS-OQAM). We present a signal model of a UW-GFDM system
considering a single and multiple UWs. We then develop an LMMSE receive filter
for signal reception of the proposed UW-GFDM system. Simulations show that the
proposed UW-GFDM system outperforms prior work.
