Closing in on the “perfect code” (2004)

30 years ago? What took so long for broad adoption? Patents? <i>edit</i> Article doesn&#x27;t elaborate on why that might be, but it does note: &quot;an alternative that has been given a new lease on life is low-density parity check (LDPC) codes, invented in the early 1960s by Robert Gallager at MIT but largely forgotten since then...Now researchers have implemented LDPC codes so that they actually outperform turbo codes and get even closer to the Shannon limit...Another advantage, perhaps the biggest of all, is that the LDPC patents have expired, so companies can use them without having to pay for intellectual-property rights.&quot;

<a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Turbo_code" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Turbo_code</a>

I worked on forward error correcting codes for a variety of systems.<p>A few big issues with Turbo codes: 1. Decoder complexity - often 4x or more the complexity of simpler codes.<p>2. Encoder delay- you need to have a really long interleaver at the transmitter to get the big dB of improvements.<p>3. These work best an pure additive white gaussian noise channels - most channels suffer from multipath, fading and other disturbances.<p>So while they are good far satellite broadcast system they don&#x27;t always work as well in other applications.

&gt; key to the next generation of multimedia cellphones<p>How is perfect data transmission a make or break feature for lossy compression and transmission of audio and video?

See also Fountain Codes, e.g. RaptorQ: <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Fountain_code" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Fountain_code</a>

In 1993, two unknown French engineers claimed to have found a coding scheme to provide virtually error-free communications at data rates and transmitting-power efficiencies well beyond what most experts thought possible. Nobody believed them and set out to find the error in their paper... There was no error.

The article is from 2004.

This should be tagged (2004)