Enhanced AMR-WB bandwidth extension in 3GPP EVS codec

This paper presents the bandwidth extension (BWE) method developed for the AMR-WB interoperable (AMR-WB IO) modes of the 3GPP EVS codec. The low-band signal (0–6.4 kHz) is coded using an enhanced version of ACELP as in AMR-WB and post-processed; the high-band (above 6.4 kHz) in contrast to AMR-WB is represented with a new BWE method. The decoded low-band excitation is adaptively extended to high frequencies and filtered in the DCT domain. The extended excitation is scaled by subframe gains and shaped by a weighted LPC synthesis filter. Test results show that the AMR-WB IO BWE contributes to the performance advantage of EVS AMR-WB IO over the original AMR-WB, with limited complexity increase and no extra delay.