Optimal rate allocation for speech enhancement using remote power-constrained wireless microphones

The problem of speech enhancement is considered in an interference environment, typical to applications like hands-free voice communication and multi-party conferencing. In the proposed system, a directional microphone placed at each interference is used to estimate the power spectral density (PSD) of the interference and the quantised PSD estimate is transmitted over a wireless link to an omnidirectional primary microphone that observes the corrupted source speech signal. At the primary microphone, the received observations are fused to obtain an estimate of the PSD of the desired speech signal. The problem of minimising transmitted power is considered subject to constraints on total transmission rate and maintaining the mean-squared error in the estimated speech signal PSD below a prescribed limit, under narrowband and broadband signal models. The optimisation problem is solved by determining the optimum rate for encoding signal PSDs. The proposed strategy is analysed using sample speech and music signals.