Low-Complexity Sliding Window Block Decoding Using Bit-Flipping for OVFDM Systems

Overlapped frequency division multiplexing (OVFDM) systems can obtain high spectral efficiency (SE), which is proportional to the constraint length. However, high decoding complexity imposes the main challenge on OVFDM systems. This paper proposes a low-complexity sliding window (SW) block decoding algorithm for OVFDM systems, where data symbols are estimated based on the reception of a SW instead of a date frame. Specifically, block code of each SW is decoded by bit-flipping algorithm where the bits to be flipped are selected according to the largest absolute value criterion. Using this criterion, the complexity to obtain the near optimal bit-flipping vector grows only linearly with the SW length. In addition, the study of the decoding algorithm is based on the design of OVFDM encoding structure, where symbols can occupy orthogonal in-phase and quadrature channels simultaneously to further improve SE by a factor of two. Simulation results show that OVFDM SW decoding with bit-flipping algorithm can be used when constraint length is relatively high (constraint length ≥ 20) because the complexity goes roughly linearly with the increase of constraint length.