AFD-DFE Using Constraint-Based RLS and Phase Noise Compensation for Uplink SC-FDMA

In this paper, we develop a constraint-based block recursive least-squares (CRLS) for an adaptive frequency-domain decision feedback equalizer (AFD-DFE) in uplink single-carrier frequency division multiple access systems. For the AFD-DFE, both the feedforward and feedback filters are implemented in the frequency domain; therefore, the CRLS complexity can be reduced substantially when compared to its time-domain counterpart by exploiting the matrix structure in the frequency domain. The performance of the CRLS algorithm is better than that of the RLS when applied to the AFD-DFE, with no increase in the computational complexity. Our designed AFD-DFE with CRLS not only enjoys a lower computational complexity when compared to the frequency-domain channel-estimate-based minimum mean square error DFE (MMSE DFE), but its performance is also better than that of the MMSE DFE with decision errors (practical case) and is close to the MMSE DFE with correct decisions (ideal case). Moreover, we iteratively compensate the transmitter and receiver phase noise using its properties in the time and frequency domains. Simulation results demonstrate the robustness of our designed AFD-DFE using CRLS.