Optimised adaptive speech coder for software defined radio

Abstract

In this paper, use of discrete wavelet transform (DWT) along with discrete cosine transform (DCT) is proposed to exploit speech coding parameters such as bit rate, compression ratio, delay and quality so as to fit the proposed coder in the family of existing speech coders'. The proposed coding technique is applied on different speech signals with fix frame size and desired bit rates. The obtained simulation result shows that the proposed coding technique outperforms in compression ratio with compatible processing delay. The mean opinion score (MOS) assessment shows its effective working at different bit rates (13 Kbps to 256 Kbps). The coder is also tested successfully on ARM 9 based software defined radio (SDR) platform at different frequency bands with desired bit rates. Hence, the coder may be considered as one size fits all type of coder for efficient utilisation of available frequency spectrum in mobile communication.