SOS-Based Blind Channel Equalization With Quadratic Complexity

Second-order blind algorithms have in common a complexity that is cubic in both the channel order and the number of receiving antennas. We present an original technique that converts (the problem of equalizing) a (multiple) channel into (that of) an equivalent channel with an impulse response shorter by one or more taps. This reversible transformation involves a negligible complexity and is repeated until a zero-order channel is obtained, hence achieving zero-forcing equalization. The overall complexity of this deterministic iterative technique is quadratic in the channel order. Simulations with a limited number of snapshots show that performance is comparable to other second-order techniques.