Fractionally Spaced Orthogonal Frequency Division Multiplexing Systems

Frequency domain equalizers using cyclic prefix have been often deployed due to their implementation efficiency and attractive performance. The design of such schemes with an L-fold fractionally spaced receiver has been recently proposed. We consider here the more generic setup where the sampler operates at L/M times the symbol rate where L > M > 1 are coprime integers. Using a multirate DSP approach, we introduce a new discrete time transceiver that i) generalizes and unifies previous work, ii) gives a complete solution to the L/M fractionally spaced receiver and the periodic non-uniformly spaced one and iii) provides new insight by relating the obtained solutions to the so-called polyphase components of the channel. Our simulation results show that the new structure delivers better performance than the standard case with comparable complexity.