Low Complexity Adaptive Turbo Frequency-Domain Channel Estimation for Single-Carrier Multi-User Detection

Adaptive turbo frequency-domain channel estimation is incorporated with low complexity turbo space-frequency equalization (TSFE) for single-carrier (SC) multi-user detection. The simplified turbo recursive least square (RLS) channel estimation algorithm provides nearly the same performance as its full complexity version, with a tremendous complexity reduction. With PSK modulations, the simplified turbo RLS channel estimation reduces to turbo LMS channel estimation. With a low training overhead, the simplified turbo RLS channel estimation provides a performance comparable to the case with perfect channel state information (CSI).