Orthogonal frequency division multiplexing (OFDM) multicarrier system is one of the most common approaches to overcome the frequency-selectivity of channels. When impulse response of channel is long the spectral efficiency of OFDM becomes very low due to using cyclic prefix (CP). Another multicarrier system, which achieves high spectral efficiency, is based on filter-bank (FB). However, due to using real symbols in high spectral efficiency FB systems, they are not suitable for multiple-input multiple-output (MIMO) techniques in which complex symbols are employed. In this paper, we proposed a new multicarrier system, in which FB and unique word OFDM (UW-OFDM) techniques are combined together; called FB-UW-OFDM. Due to using complex symbols in the FB-UW-OFDM, the space-time coding scheme can be employed. The proposed system is following the approach of [1] (we call it FB-CP-OFDM) in which CP-OFDM techniques has been used instead of UW-OFDM. Based computer simulations although the FB-UW-OFDM system has the same bandwidth efficiency of FB-CP-OFDM, it has better performance. Moreover, employing UW-OFDM provides the possibility of channel estimation and synchronization due to using a deterministic unique word in FB-UW-OFDM system.

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