Quantization is basically the method of mapping a big set of input values to a smaller set, widely utilized in almost all the digital signal processing as it represents the signal in digital form. Aspect of data compression or coding is to shrink the number of bits necessary to deliver analog data, dependent on a distortion or fidelity conditions. In a wired communications very large bandwidth (range of frequency) are obtainable due to enormous bandwidth availability of optical fiber cables, while in a wireless communications range of frequency spectrum availability is a significant matters and service provider are continuously in penetrating of coder for obliging more consumers within a limited allocated spectrum. To achieve high speech quality at a lower bit rate coding algorithms plays a vital role to remove irrelevant information (redundancy) from speech signal. Good-looking progress have been made during last decades in code the speech signal with high quality at low bit rate for next generation wireless communication. This 1paper provides the fundamentals of scalar & vector quantizers applied for analysis and synthesis of speech signal. This paper also includes the review regarding the various types of coders utilized in next generation wireless communication as well as current capability in research direction in speech coding techniques.
Adaptive variable bit-rate speech coder for wireless applications