Low Power Microarchitecture Designs of ACS Block in Viterbi Decoder: A Review

Low-power microarchitecture designs of Viterbi decoder are considered one of the on-demanding issues in Very Large-Scale Integration (VLSI). Viterbi decoders consume 35% of the power and 76% of the complexity in digital communication schemes, e.g., IEEE 802.11 a/g WLAN schemes. Development of Viterbi decoder itself reduces dramatically system complexity; the decoder has a source of power sink unit which rises in Add Compare-Select (ACS) unit. Various levels of development exist in VLSI such as architecture, microarchitecture, circuit, and transistor. ACS is structured of adder, comparator, and selector, so microarchitecture development of ACS unit intends one of these superior blocks. Adders in VLSI designs have a tremendous interest as they are the kernel of any digital system so enhancing this basic building block, which is used over and over, influences system specification. This paper targets different microarchitectural approaches to shrink the power of this unit which enhances overall system specification. Microarchitecture development encompasses using another block instead of the existing one or repositioning current blocks. In this review paper, comparisons of different parallel adders are presented to achieve low consumption power while obtaining high-speed operation of the addition, and an arrangement of ACS blocks to reduce the complexity of the decoder is also provided.