A Simplified Computational Kernel for Trellis-Based Decoding

Abstract

Link to publicationCitation for published version (APA): Kamuf, M., Anderson, J. B., & Öwall, V. (2004). A simplified computational kernel for trellis-based decoding. IEEE Communications Letters, 8(3), 156-158. DOI: 10.1109/LCOMM.2004 General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal Take down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Abstract-A simplified branch metric and add-compare-select (ACS) unit is presented for use in trellis-based decoding architectures. The simplification is based on a complementary property of best feedforward and some systematic feedback encoders. As a result, one adder is saved in every other ACS unit. Furthermore, only half the branch metrics have to be calculated. It is shown that this simplification becomes especially beneficial for rate 1/2 convolutional codes. Consequently, area and power consumption will be reduced in a hardware implementation.Index Terms-Add-compare-select (ACS), branch metric, logMAP, very large-scale integration (VLSI), Viterbi decoding.

Design and measurement of a variable-rate Viterbi decoder in 130-nm digital CMOS

“…Supported code rates are 1/2 and 1/3. Code rate is not a critical design parameter when used with antipodal constellations such as BPSK and QPSK since the calculation of distances to the 2 c code sequences is very simple [13]. However, the design does not explicitly provide puncturing resources to enable high-rate transmission.…”

“…In an AWGN channel, the optimal distance measure is the squared Euclidean distance between received channel symbol y ¼ ðy I ; y Q Þ and constellation symbol s, that is, jy À sj 2 . For antipodal signaling this expression is reformulated to additions and subtractions of the channel symbols [13]. Channel symbols are quantized with q ¼ 3 bits without causing much performance degradation [9].…”

Area and Power Efficient Trellis Computational Blocks in 0.13μm CMOS

“…In an earlier paper [5], we used this property and presented architectural simplifications for these units. Here, we apply this idea to see how these arithmetic savings translate into area and power savings in a silicon implementation.…”