By any measure, turbo codes have been a staggering success. Before the turbo revolution, 2G cell phones used “soft decoding” (i.e., probabilities) but not belief propagation. 3G cell phones used Berrou’s turbo codes, and 4G phones used Gallager’s turbo-like codes. From the consumer’s viewpoint, this means that your cell phone uses less energy and the battery lasts longer, because coding and decoding are your cell phone’s most energy-intensive processes. Also, better codes mean that you do not have to be as close to a cell tower to get high-quality transmission. In other words, Bayesian
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