Globally convergent adaptive blind filters and blind equalisers for mixed-phase channels
JITENDRA K. TUGNAIT · IEE Proceedings - Communications · 1994
A new approach is proposed for recursive estimation of the parameters of finite-impulse response and infinite-impulse-response nongaussian signals which are assumed to be generated by driving a finite-dimensional channel (system) by an IID nongaussian sequence. The problem is addressed in a blind setting, i.e. only the channel output is observed, not the input to it. The signal model is allowed to be nonminimum phase; hence the model is applicable to the problem of blind channel equalisation in data communication systems. The proposed recursive parameter estimator is shown to be globally convergent, i.e. the parameter estimator converges to the true model regardless of its initialisation. Therefore, the blind-equaliser design based on the estimated channel parameters is also globally convergent. The proposed parameter estimator is based on a two-model decomposition approach: a spectrally equivalent minimum-phase system in cascade with an allpass system. An illustrative computer-simulation example using a 16-QAM signal is presented where the proposed approach is compared with a Godard blind equaliser.