Speech coding for wireless communication

Personal communication systems will be judged primarily on the quality of speech communication they provide. The voice-call capacity depends directly on the bit-rate required to achieve the quality objectives of the specific service. To provide speech quality on wireless systems that is comparable to that attained on today´s wireline systems, at least 16 kb/s are required. New algorithms are being considered for a standard to transmit speech at 8 kb/s in the presence of modest transmission errors. Mobile systems with slightly lower quality requirements in service today employ 8 kb/s (IS-54 and IS-95) and 13 kb/s (GSM), respectively. Efforts are under way to halve these values and thereby double the capacity. The paper reviews current research into achieving higher speech quality at lower bit rates under a variety of environmental and transmission conditions. It provides a short-range perspective on where significant progress is expected in the short-term