Performance costs for theoretical minimal-length equalizers

The length and complexity of a linear equalizer filter is highly dependent on the nature of the channel effects it must mitigate. The governing design rules are typically stated in terms of the channel's temporal characteristics, i.e. impulse response duration. Equalizer implementational complexity is a principal limiting factor for high bandwidth data communication applications, and consequently there is motivation for reexamining accepted design guidelines. Recently, it was demonstrated in [1] that for relatively benign conditions on the effective channel and transmitter pulse shaping, there exists a linear equalizer that perfectly mitigates intersymbol interference, and whose span matches that of the composite distortion. Our paper examines the implications of the minimal-length equalizer in light of accepted design rules, and shows that a tangible loss in performance can be assigned to this complexity reduction. Actual line-of-sight microwave radio channels are used to demonstrate the nature of the performance loss.