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On Iterative Decoding Of Two-Level Superposition Codes For Cooperative Broadcasting Based On Qpsk And 4-Pam Constellations, Robert H. Morelos-Zaragoza
On Iterative Decoding Of Two-Level Superposition Codes For Cooperative Broadcasting Based On Qpsk And 4-Pam Constellations, Robert H. Morelos-Zaragoza
Faculty Publications
This paper considers iterative decoding of two-level superposition codes used in cooperative broadcasting over wireless networks. The coding scheme consists of two low-density parity-check (LDPC) codes combined using Plotkin's |u|u + v|-construction and provides two levels of error protection. Coding for cooperative broadcasting differs from conventional single-source broadcast coding. Instead of binary addition of subcode codewords performed by a single-source encoder, in superposition coding two modulated subcode sequences, produced by two coordinated and independent sources, are combined at the antenna of the receiver. Expressions are derived for the bit metrics, or log-likelihood ratio values, used by an iterative decoder for …
A Two-Stage Decoder For Pragmatic Trellis-Coded M-Psk Modulation Using A Symbol Transformation, Robert H. Morelos-Zaragoza, Advait Mogre
A Two-Stage Decoder For Pragmatic Trellis-Coded M-Psk Modulation Using A Symbol Transformation, Robert H. Morelos-Zaragoza, Advait Mogre
Faculty Publications
A two-stage decoding procedure for pragmatic trellis-coded modulation (TCM) is introduced. It applies a transformation from the received I-channel and Q-channel samples onto points in a two-dimensional (2-D) signal space that contains a coset constellation. For pragmatic TCM over M-PSK signal sets with ν coded bits per symbol, ν=1, 2, the signal points in the coset constellations represent cosets of a B/QPSK signal subset-associated with the coded bits-in the original M-PSK signal constellation. A conventional Viterbi decoder operates on the transformed symbols to estimate the coded bits. After reencoding these bits, the uncoded bits are estimated in a second stage, …
Qpsk Block-Modulation Codes For Unequal Error Protection, Robert H. Morelos-Zaragoza, Shu Lin
Qpsk Block-Modulation Codes For Unequal Error Protection, Robert H. Morelos-Zaragoza, Shu Lin
Faculty Publications
Unequal error protection (UEP) codes find applications in broadcast channels, as well as in other digital communication systems, where messages have different degrees of importance. Binary linear UEP (LUEP) codes combined with a Gray mapped QPSK signal set are used to obtain new efficient QPSK block-modulation codes for unequal error protection. Several examples of QPSK modulation codes that have the same minimum squared Euclidean distance as the best QPSK modulation codes, of the same rate and length, are given. In the new constructions of QPSK block-modulation codes, even-length binary LUEP codes are used. Good even-length binary LUEP codes are obtained …
Block Qpsk Modulation Codes With Two Levels Of Error Protection, Robert H. Morelos-Zaragoza, Shu Lin
Block Qpsk Modulation Codes With Two Levels Of Error Protection, Robert H. Morelos-Zaragoza, Shu Lin
Faculty Publications
A class of block QPSK modulation codes for unequal error protection (UEP) is presented. These codes are particularly suitable either for broadcast channels or for communication systems where parts of the information messages are more important than others. An example of the latter is coded speech transmission. Not much is known on the application of block UEP codes in combined coding and modulation schemes. We exhibit a method to combine binary linear UEP (LUEP) block codes of even length, using a Gray mapping, with a QPSK signal set to construct efficient block QPSK modulation codes with nonuniform error protection capabilities …